the iron hemi heads are where all the weight is!!
i know they are expensive but why not run the mag crossram from A&A??
we used it on the Mr. Norms motor (and all the others) its a 472 with 300ish duration @ .050 and 700+ valve lift, 12.5:1 comp spinning it to 6500 and the manifold wasn't a restiction! were using the correct carbs for 68 and jetted it just like the MP book said to for a original race hemi... it was to fat all around by like 5 jets!