how thick of a Headgasket can you put on there? If you put in one that is like .12" into that formula, you'll be down to 8.5:1 CR.
I know the VW guys put pretty thick headgaskets on their vr6 motors to drop the CR & turn up the boost, but I don't know how thick. I think they drop the CR from 10.1:1 to 9.0:1, roughly 1 full point (depending on the specific app).
more info here