I think this drawing is the correct one. We see head rest in front view wind shield. https://forum.warthunder.com/index.php?/topic/197784-sai-ambrosini-ss4/
This aircraft had a complicated front wing.
I imagine that this aircraft had engine cooling problem at zero speed /taxing condition, too.
" spec metric english
wingspan 12.32 meters 40 feet 5 inches
wing area 17.5 sq_meters 188.4 sq_feet
length 6.74 meters 22 feet 2 inches
height 2.48 meters 8 feet 2 inches
empty weight 1,800 kilograms 3,968 pounds
normal loaded weight 2,446 kilograms 5,392 pounds
max speed at altitude 540 KPH 335 MPH / 290 KT
The program came to an abrupt end the next day, 8 March, when Colombo took the machine up for a second flight. An aileron malfunctioned and Colombo tried to set the machine down in available open space; he ran into a tree and was killed, with the aircraft totaled. There was some consideration of building a second prototype, but it didn't happen. The initial flight had not demonstrated any particular superiority to fighter aircraft of conventional configuration, and there had been increasing misgivings about the project anyway. How was the pilot to bail out, for example, without getting chopped to pieces by the rear-mounted propeller? There were also concerns about engine cooling, rearward view, and that the engine would crush the pilot if the aircraft ran into something on the ground. Steffanutti went on to develop lightweight fighter aircraft of conventional configuration."
Large three side view drawings
SAI Ambrosini S.404
https://it.wikipedia.org/wiki/SAI_Ambrosini_404 Auto translation
"During the competition of 1938 for a military aviation authorities held B.G.R. participated: Caproni Ca. 204 and Ca. 211, The Cantieri Riuniti dell'adriatico (C.R.D.A.) with the CANT z. 1014, FIAT with g. 30B, Piaggio with p. 112 and Sai Ambrosini which he compiled an innovative aircraft, the s. 404, inspired by the experience of 30 years of engineer Luigi Stipa.
Luigi Stipa, in fact, flew its Stipa-Caproni which was characterized by a sort of fuselage-nacelle-tunnel enclosing engine and propeller to increase efficiency of the propulsion system, giving the characteristic name turbine wing plane, then called ducted propeller. This aircraft was jokingly labeled "troublemakers" or "plane plane barrel";
' plane which can be regarded as a forerunner of aircraft. "
("High Speed Aerodynamics and Jet Propulsion" ed. Princetown University Press)
To it, as mentioned, was inspired by the design of the s. 404. According to one source, deserving of further checks, the Sai-Ambrosini 404 was flown on 19 September 1940 to March 1941 and tested by the November 20, 1940 with the armament. His poor flying qualities, especially at low speeds, the aircraft was unmanoeuvrable, together with the tendency to overheating of motors in tandem, made faint interest military bodies. Technical dscription
S.404 had a metal structure with welded steel tubing for the fuselage while the wings were built instead of aluminum, were planned 8 crewmen. It had a wingspan of 24 m, with a total surface area of 90 m ² a wing loading of 178 kg/m ² and with an overall length of 12.9 m; It was also an unbraced twin tail. The payload was expected to 9000 kg, while that at full load was 16 276 kg. Engine
It was fitted with Isotta Fraschini Asso XI engines 4 gearless from 840 HP, seats in tandem in the fuselage of the bomber. Three-blade contra-rotating propellers through four, placed in tandem at the entrance of the two side tubes, had a good rate of climb and takeoff. Engine cooling radiator was placed on the inner surface of pipes with the ability to shut off the flow over it. The aircraft had a top speed of 475 km/h and a maximum range of 4000 km. Armament
Its armament was 12.7 mm machine guns 8 with 400 rounds per gun. Operational history
Had no operational use; its development was stopped for her poor flying qualities and for the tendency to overheating of motors.
The Leonardo da Vinci Museum in Milan is a life-sized model of a ducted propeller engined reminiscent of SAI Ambrosini 404. Variants
Would result from historical archive funds AM-Direction Aircraft» the existence of two 404 built or designed by SAI Ambrosini, SAI ambrosini 404 large RADIUS bomber, described above, and the single-seater fighter Aircraft engine SAI Ambrosini s. 404 Isotta Fraschini Zeta from 1 200-1 400 HP,  the latter designed in August 1942, with estimated speed of 670 km/h and armed with two 12.7 mm machine guns and two 20 Safat from Mauser from mm. "
"Draft heavy bomber S.A.I. s. 404 was offered as part of a competition in the year 1938 Regia Aeronautica. Unlike other competitors offering quite traditional schemes and trehmotornyh four-engined aircraft company Societa Aeronautica Italiana (Ambrosini) offered one of the most original projects. The new bomber was based on experience gained in designing and testing of experimental aircraft "Stipa". Despite the fact that in 1933 year project cancelled in mind poor indicators firm Ambrosini still struggled to receive much better performance.
The project S. 404-fuselage concept lay pipes installed inside the engine with a tractor propeller. In 1938 year scheme largely finalized. For the bomber was developed a short and wide fuselage, fuselage sides which were fixed tunnel sections. The engines were mounted inside the fuselage, and inside the "tunnels" were only screws. At the ends of the sections was the tailplane (twin). The main wheels folded chassis and rack in the lower part of the tunnel section and fuselage, tail wheel-tail niche.
The powerplant consisted of four radial engine Isotta Frascini "Asso" (840 HP) Although the total power s. 404 looked worse, its takeoff weight was estimated at 16276 kg that was 4.5 -8.5 tonnes less competitors. Bomber design speed was approximately 475 km/h and at an altitude of 4000 meters
The s. 404 anticipated four firing points with a total number of seven 12.7 mm 0.303 machine guns. In the fore cabin Navigator installed one machine gun, and in the tail and two nadkryl′evyh turelâh had two machine guns. According to the technical requirements of the bomb load was 2000 kg.
Consideration of the project took place in the year 1939. Representatives from D.G.C.A. (Direzione Generale delle Costruzioni) very ambiguously regarded s. 404, questionable aerodynamics of aircraft, as well as landing and maneuverability at low speeds. As a result, the project was cancelled, and major efforts have concentrated on the traditional scheme”
"Stefanutti (quello degli Aerfer ) nel settembre 1942 presento' il progetto di un caccia stratosferico per intercettare i bombardieri americani. Progetto totalmente originale aveva la cabina stagna, elica di grosse dimensioni, impianti di riscaldamento, guscio centrale della fusoliera blindato con acciaio 6mm, trasparenti di grosso spessore. Motore IF Zeta RC110 1200cv a vari ristabilimenti di potenza. Velocita' stimata in 660km/h , carico alare di soli 132 kg/mq , salita a 10000 in 13'48", tangenza 14300. Armamento vario ...da 4x20 a 4 da 12.7+2x20 .
"Il tutto era probabilmente classificato SAI 307 . Benche le caratteristiche mi paiono assai ottimiste ( l'aereo era mi paiono pesante , 3820 kg e il motore non troppo prestante ) il progetto era interessante anche se ovviamente era troppo tardi per svilupparlo."
My Italian is not very good, but I have translated the above as follows.
"In September 1942, Stefanutti (the one with Aerfer) presented his project for a stratospheric fighter to intercept American bombers. This totally original project had a pressure cabin, a large propeller, a heating system, and a cockpit with 6-mm steel armor and very thick transparencies. A 1200-hp Isotta-Fraschini Zeta RC110 engine “with various power recoveries.” Top speed was estimated at 660km/h, wing loading at 132 kg/sq-m, rate of climb to 10000 m at 13 minutes, 48 seconds, and service ceiling at 14,300 m. Armament varied from 4x20-mm cannon to 2x20-mm cannon plus 4x12.7-mm machine guns.
"The whole was probably classified as the SAI 307. Although the [quoted] characteristics seem rather optimistic (the airplane would have been pretty heavy, 3820 kg and the engine none too strong), the project is interesting although obviously too late for development."
The phrase "a vari ristabilimenti di potenza" (“with various power recoveries”?) puzzles me. But I think it must refer to the engine supercharger's ability to maintain power up to and beyond its critical altitude.
I think that the supercharger was likely mechanical rather than an exhaust-driven turbo. Although the drawing does not rule out the latter, I think it looks more like a Daimler-Benz type hydraulically driven mechanical supercharger.