I would think that an even .030 gap would be taken up by the intake gaskets nicely.
I am no familiar with the magnum configuration.
Are the intake manifold bolt holes in the head blind or do they extend into the water jacket in the head?
They extend straight down into the head/lifter valley i.e. If I were to take a bolt out and pour oil down the bolt holes it'd run into the lifter valley. No water jacket. The outside bolts just run to the outside of the heads.
