To find out what the compressed thickness of a head gasket is, place a small lead pellet in an appropriate location and torque down the head. Pull the head off and measure the pellet.

I had cast pistons (can't remember brand or part #, again nothing special) with very little chamfer around the top, zero deck, "normal" valve pockets, file fit rings, Fel-Pro .039" thick gaskets, ported #16 heads, RA IV cam and 1.5 rockers, stock 4 bbl intake and Q-jet, recurved dist., three tube headers, 2.5 duals and Sonic Turbo mufflers, three core rad with shroud and five blade stainless flex fan, TH400 and 2.56 gears in one car, T10 and 3.23 gears in another. 3000 feet above sea level, premium unleaded, no overheating or detonation problems ever, lots of highly illegal top end blasts for a few miles and extended highway runs averaging 85-90 mph in mostly 80 - 85 F temps max, engine made good power and mileage, 36 degrees total all in by 3000 rpm.