whats your dynamic compression and cylinder pressure? I have a 10:1 motor with about a 7.9 dynamic comp and she does just fine at 100oct (50/50 mix of pump 91 and 110 leaded)
so..I have 10.1 static and 8.8 dynamic and run on 91 with close chambered heads. I would say cylinder pressure plays a big part in it all.. Also this engine was built by Brian at IMM. 33 degrees timing.