So we're clear, we're talking about the British Mustang MkIa with the 4x20mm hispano cannons, the Allison engine that topped out at 382 mph, had the older canopy, and NO ordnance options. About 111 ended up serialized with the RAF in this configuration - probably less actually made it in the air.
What exactly would make this version a more popular version compared to the P-51B that is mostly a hangar queen? And with it's smaller wing area, it's not going to turn as well as the P-51B/D and has a climb rate of 3000ft/s.