540CI, 8.0:1 compression, max 8-9psi of boost, 850-900hp pump gas hyd roller 6000rpm max. Engines are in a heavy twin engine 38 Cigarette. We removed heads last night, as the valve leakage was excessive. Heads are in shop for rebuild. Head gaskets were showing signs of possibly a little leakage between cylinders. Previous engine assembler used a lot of copper rtv on the decks/heads when assembling with cometic MLS. Anyhow, the pistons are out of the hole about .005. I suggested getting Felpro MLS .053 thick as replacements. I like the coating on the felpros over the cometics personally. Both block and heads have proper RA finish. Cylinder head guy suggested standard composition type gaskets, but, I only see felpro has one thickness with the 1047 or 10748 stainless fire rings, and that's .039. I think that might be a little too tight for my liking with the pistons where they are. Any thoughts? He would like to not have these heads back off for a while.