Hi Vietcong!
I think it's not so easy - to transform a light aircraft with 240-hp engines, with only 320 km/h maximum speed, into a jet fighter flying 3 times faster. If you want to do this, you need to strengthen and, in fact, to redesign all the internal structure! Even if your result would look much like Ho VII, it would not be Ho VII anymore. It would be a new aircraft.
And, to my mind, we can say that Hortens actually did somewhat like your proposition... and named the result "Ho IX" ! Actually, Ho VII and IX are very close to each other in size and geometry. Ho VII was 7.50 m long, Ho IX was 7.465 m. The wingspan of Ho VII was 16.0 m, wing area 44 m2; Ho IX initial project - 16.0 m and 46 m2! (Later, because the planned BMW 003 engines weren't available and Hortens had to redesign Ho IX for Jumo 004s, its wingspan increased to 16.8 m and wing area to 51.8 m2). But, empty Ho VII weighed 1550 kg, while Ho IX V2 - already 4844 kg. Takeoff weights are, accordingly, 2000 and 6876 kg. The Ho IX had to carry 1700 kg of fuel, instead of Ho VII's 290 kg: the "appetite" of Jumos was incomparable with little piston Arguses.
