My 505 uses the 440 source 7.1" rod kit with the 17cc dish pistons, but I had the block milled to zero deck with the pistons, used the standard Fel-Pro 8519-PT1 head gasket (it has a larger bore size for the stealth heads), and 84cc Stealth heads for a compression ratio of 10.33:1.

With 74cc heads, 0.010" in below deck and the 0.027 Cometic gasket, I get 11.34:1 compression.
With the 0.039" 1009 Fel-Pro gasket, 11.02:1 compression.

I think the slightly higher compression with good quench would be better than the slightly lower compression ratio and less quench.

If your cam is larger than 290 degrees duration (and not installed advanced), you should be OK on pump premium if you keep the intake air cool and engine temps do not get too high.