I hope I didn't miss read something but I do it this way.
I don't do the correction by cutting the intake manifold, I cut the intake side of the cylinder head to correct intake manifold fit. By doing that you can change to different intakes and the manifold won't be engine specific. If you deck your block and heads keep track of what is removed then correct that by cutting the intake surface of the head. Their is a certian amount that needs to be removed on the extreme lower edge of the intake flange that I take off by using a platen surfacer so the intake will set down properly when cut.

logan426