my 360 build.

915 heads? What’s the cc of the combustion chamber? What year is the block. I think most blocks are 9.60 in height so with the pistons you chose that puts you at 9.573 so 0.027 in the hole (assuming factory deck height and no machining has been done to the deck) If you know the CC’s of the head and head gasket thickness we can nail down your compression, but sounds like you should be in the 9.5:1 area which should be good for those iron heads.