I have flat tops in the Duster and I'm using the same heads I had on the Duster and even that I had to use premium with a tickle of race gas...
I want to be able to use straight junk gas and not think twice...
I have enough heads, that I think I can adjust for several points of compression, with selective head gaskets.
I managed to get my last flat top engine down to 10.8 static and it ran on pump gas, that was with 58cc heads. Look real hard at the intake closing on the cam, that will make a difference in dynamic compression. (real world).
