Until we get a casting number from the OP, it's a guessing game LOL. No way to know if these are original heads or ???? 'til that is known.
Hey AJ, my intent was to dispute the 7:1 SCR number posted earlier.....920's would be even higher SCR than what I showed with 675 heads.
So again.... the OP can help himself and everyone to post some pix and part numbers so we really know what he is starting with. We also need to know if he intends to replace the pistons due to bore wear. Not many choices out there.