Figuring a .005 deck height and a .040 thick head gasket with a flat top piston with no valve reliefs, a large chamber head at 72cc's will give you 9.69:1 compression. So you might be at the upper limit even with the premium pump gas, but should be good for your N/A combo.
Ok, how about when he wants to lower the compression ratio w/the same pistons installed for the turbo application?
What are his options?
