Hank
As you go bigger than stock bore you run into head gasket issues, the OEM gasket is a 3 layer steel - like a cometic and the fire ring is only 0.010 to 0.015" bigger than the bore.
The alternative is to goto a copper head gasket and o ring the engine then you can go bigger - say 0.060 OS as still have decent dry wall/sleeve thickness. I'd have to do some measurements to confirm this number.
With good cams and a ported late head, need power - run it harder. Some of the comp eliminator guys are turning >9800 though the traps... mind you this is a full race engine that doesn't have to last many miles between teardowns.
Being a 6 it still has the nasty harmonic issue - got to be able to buzz past it and keep the rpm above the harmoinic point.
