Here's the scoop:

Pistons are .019 in the hole. I had planned on a set of AFR heads, but I don't think I should use a steel shim with the aluminum heads. Would I be better of to go with the .028 GMPP gasket with the AFR heads and .047 quench, or should I stick with iron heads and the steel shim gasket with .039 quench.

C.R with the 68cc AFR's and an .028 gasket will be 10.25:1
C.R with the 72cc Iron heads and an .020 gasket will be 10:1

I was trying to get closer to 10.5:1 C.R. using the AFR heads with an .020 gasket, but all I can find are steel shims or copper.