Not sure how accurate Summit's compression calculator is, but this is what I've been using. Been playing with some numbers and with my pistons .070 in the hole and using .020 head gaskets, this is what I've come up with. Using 88cc's as the reference for the open chambered heads I get 9.22 compression. Using 84cc's for the closed chambered heads I get 9.52. Of course I will have to cc the chambers to know exactly what I have, but I thought this would give me a ballpark figure. If the cc's on the heads are less, then of course the number goes up obviously.