[cbeerman]

You want a 2 bbl V6 intake (from a 305E) and a carb adapter. The magnum intakes have a trapezoidal carb flange, larger size ports, and no divider between the adjacent ports.

Using that intake you would have some port misalignment on standard heads kind of like if you bolted oval port BBC manifold on a set of BBC peanut port heads

To complicate the magnum swap, they don't make a carb adapter for the Magnum intake anymore (Transdapt PN 2140) and the magnum gaskets are hard to come by although some claim the standard gaskets will work.