I'll give some feedback from my car I ran last year. On the STF Mini I ran, I would run race tires at BMW events. 225/50-15 R1-S tires on 15x9F and 15x7.5R. Balance was decent. Eventually I switched over to the 14x6 miata wheels I had with very old 225 710s. This was a bit too much oversteer.
IMO if I had 15x10-11 up front on a 275 Hooiser with the 225 on a 7.5-8 it would have been nice. The 8 out back would be ideal IMO. To me this would pinch the 225 a little bit and keep it tucked. But still allow some movement for rotation but not so much to be evil. And the slightly pinched tire would be a bit forgiving out back. 205s IMO are too narrow on a properly setup mini.
As for front wheels the 949s are the best bang for the buck.
Option B already stated would be 15x10 front and with 245s. If on a budget this might work well. And be less scrub. Something to test at least