I knew a Super Stock racer back in the day that helped me on some info when I bought my 65 lightweight Dodge. He lived in Homa, La so I got to watch and hang around him back in the day of class racing when there was lots of class racing. He raced SS/BA in his 65. The 65 hemi came with alum heads. He found some obscure bulletin from Chrysler that allowed the 64 iron head as a replacement for the 65 alum head. The heads were identical except for the material. He said he always ran the iron heads because they were faster. They held the heat better and the heat meant more power on the dragstrip in class racing. I think they ended up using the street hemi heads because they were more plentiful and legal too. I’ve seen him win class several times. He raced out of the Southland Dodge group. I bet the Teuton’s could probably add some input on this as well.

Now, on the street, it may be different. I know all the cars now have aluminum heads and higher operating temps for better fuel mileage. But that is sustained driving. Dyno results could be tailored to show either.

Interesting discussion. I’m building a 340 for my friend with ported X heads that gets hot because they were ported too much. I sold him a virgin set of X heads for his matching numbered car but he may go with alum on this build.