Another "recommend a cylinder head?" thread!

Back off your total timing till it stops knocking, I have run 11:1 at 28 degrees with pump gas. Detonation is caused by high temps, high temps are cause by high pressure. Higher timing causes higher pressure, higher pressure causes higher temps. It's very simple a motor with higher CR is more efficient. Timing is a variable, so back it down. It will run great and you can't run the timing at factory spec because the motor is no longer at factory spec.