ProComp/Speedmaster aluminum heads

All the research I did and the best I can find out the 596 heads had anywhere from a 68 to 72 CC average. 70 CC is about what I believe them to be.
And of course those are open chamber. I used a 1008 Fel Pro .039. my open chamber heads were gasket matched in countersunk just it's managed to make sure the Pistons had plenty of room. Now of course I'm going to the closed chamber heads and considering using the suggested 8553 Fel Pro.053. hoping that that will get me extra .030 Clarence that I believe you're supposed to have piston to head?..
I was wondering because I haven't used them before if closed heads have any kind of different performance characteristics than open chamber besides compression?