Larry
If I read your post right you started with 12-1 pistons then fly cut them for valve clearance. This would lower your compression ratio not increase it. Normally anything over 13-1 would run on fuel such as alcohol. I have a 254 cu in six running 10.3 -1 and with timing set for performance it will ping some on 89 octane but runs fine on 92. I run a comp cam and msd ign including disributor 6A box and blaster coil.
Most vehicles that come from the factory with a compression ratio above 10-1 are marked on the fuel gauge to use premium fuel only.
Big Bill
Been there, Done that, Hope to live long enough to do it again.
Big Bill
I.I.# 4698
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