head issues and how much to cut off the intake.
I had the same issue when I put my Eddy heads on my small block. I found that my Air Gap intake was slightly to tall. The intake bolts would just start to grab but were to the top side of the hole. I knew something was up and didn't force them. I didn't even have the heads cut and still the intake would't fit right. I was told by Edelbrock that all castings are not exact and that in some cases the manifolds need to be cut. I was sure surprised to hear that. I ended up taking 0.40 off my intake to get the bolts to go in like they should. I also heard that this isn't all that uncommon on small block Chevies with aluminum heads. I had a shade tree mechanic tell me to "just elongate the holes" I THINK NOT! Machining it was the only way to go!
The odd part is that a friend of mine with the exact same setup put his intake on and it went on without any problems at all. As far as a way to measure exactly, I had to make a educated guess on the conservative side so if I need more I could do it. I suppose you could somehow use calipers and measure the difference in the holes center to center and go from there, but I'm not sure.
Anyway I hope it all works out for you.
Ron