Racingjunk Forums - vortec heads/ general sbc question

I bought a set of vortec heads (new gm) for a a low comp. goodwrench motor i am using. I also purchased a new Edelbrock eps intake (vortec style) i have not installed them yet, i set the heads and intake on a 72 400 bare block to mock up and check them out. My problem is there is a 1/8th inch gap between the heads and intake. seems like to much. I have no head gaskets instaled either. I am sure the block has never been decked. why do i have such a poor fit? I do not intend to use them on the 400 but i have no reason to believe the fit will be any better on the goodwrench motor that i purchased them for.