dierks321,
Did you install the three metal alignment rings between the intake ports in the manifold and the head? If yes, you might need to grind the rings down a little to make up for material removed from grinding the manifold and/or head mating surface(s).
Also, the thichness of the original manifold gasaket was almost twice that of gaskets now sold (I know this from a NOS set of original gaskets). You could try using two manifold gaskets (and maybe use the hi-temp copper-colored gasket seal available at auto supply stores).
Tim
