head gasket and deck question

Guitar's dead on. Using Ross's info is misleading, because of the existing height of your factory block. The one I checked this week for a 493 was .028" taller than blueprint spec. So, saying "I have had it set to zero deck height" could mean down in the hole if the block was only decked for flatness. If the block is square decked to blueprint spec, the piston will be down in the hole .017 if I read right. If it's race only, I would run tighter than .038 unless the rpm is way high. The flat top and Indys better chamber will work very well, but there comes a level where high is too high. If this is an RB block, I would not go over 12.5:1 for longevity's sake. If it's a B block base, you can go higher. A lot depends on the work done to the lower end. A 511 doesnt need rpm to make it's power, and the lower the rpm range, the longer it will live, regardless of the static compression ratio.