For GM heads Dart has a special intake. You put GM after the part number. These intakes are milled .060" from the factory.

try sitting the manifold on with out any gasket and check to see how the bolt holes & ports aline up make shure that the intake is not resting on the china walls .if the bolt holes aline up have the manifold milled .060

try that

intakes
 

thanks everyone for you're input on this problem, i have it pretty well figured out thanks to the information i received on this site.