If on this site are all true https://仮想艦隊.jp/cms/blog5.php?itemid=125 - Taiho seems be lighter version of G-14 . G-14 have an open-hangar and armoured bridge anti -aircraft bomb until 500 kg .
It's the artist's interpretation. the text says he knows the same data as we: 45-50.000tons displacement, 3ships to be built and an aircraft component of 63 aircraft with an extra 21 spares. From this he deducted that this design would be an attack carrier or froward air base and not a support one like Shinano. Then he examined the Midway and Gibraltar classes as these were in the same tonnage range as G-14 and while Gibraltar had deck edge elevators on the left side he decided it would be better to put them on both sides.
Myself too played with the idea of deck edge elevators but the IJN seems to be not really thought about this aspect or not found them useful or we just lack info on it.
Shinano too would been originally a fully enclosed carrier but after Taiho sunk, the design altered to became more open hangered? (Is there such a word? ) So I assume the same would had happenned with this G-14 design: A Shinano sized Taiho with alterations for some open hanger space during construction. Likely 3 elevators in my opinion.