Slow build 71 Scamp 440

Even the old 516 close chambered heads still usually measure out closer to 80-82cc if they use stock valves and haven't been shaved.

Edelbrock makes two versions (E-Street, and RPM) with a 75cc chamber-they also make an 84cc and 88cc version (unless Hughes is selling the RPM misstated as 75cc...Summit says they're 84cc). You're correct, that if you bolt on a set of 75cc (trued), they would yield over 10:1 even with an .050"x4.5" gasket and the assumed piston deck clearance of 0.021".

All the above being said, if I were to go to the expense of buying closed chamber aluminum heads, I'd deck the block where the pistons were zeroed and let the quench work for me with about an .040-.045" gasket