I've had every block I have built cut from .008 to .016 and have yet to find an intake that required modification to line up. That is with stock type heads and aftermarket intakes. I have some mis-match on the 351C in the dragster but it's running AFD heads from Australia with a Funnelweb, also from AUS. They are a far departure from stock and the misalignment has nothing to do with decking the block. Bone stock block, bone stock iron intake - maybe you'd end up with the Ford guidelines. But - note that the published Ford dimensions are always "nominal" and that actual production varies quite a bit.