I think the big decision comes with how much $ to freshen the iron heads. As others said tanking, Magging, valve job , guides new valve, springs, porting and you are almost there there for a set of aluminum heads. Then grab one and set it on the flow bench, then grab an aluminum one that flows the same and put on the flow bench
Why I have edellbrock heads on the 455 I built for the 81 vs to ported 6X's!