if you can get your mate with a lathe to knife edge your A15
then have it balanced for little investment you will spin
as fast as a stock a12 crank but have more bank for your buck.

Local jp guys were and still are revving their drag race A15
engine to 10k rpm!!!!! 78mm bores will compliment it nicely.

My A15 with 36mm keihins and 79mm bores was often mistaken
for a rotary engine everywhere.