This would be a very long story if I started from the beginning so I will cut to the chase.
I bought a rebuilt 383 and ran it but it had a bad vacuum leak at the intake. I tried performance intake gaskets, swapped intakes, swapped heads, and had the deck checked. I am at a point where I am pretty sure the block was heavily decked to get the pistons close to zero and now the intake probably needs to be milled.
The question is, if you don't know how much the block was decked, how do you figure out how to mill the intake, or can you?