Jim, the test would be the octane test. If you have to run supreme in your iron head combo, but your aluminum head combo didn't need that. Cliff's car ran quicker and faster with 89 than 93 with 10.5:1 compression.
I think the results of the test that you were talking about is probably because the aluminum heads had design features that improved the performance enough to offset the heat disappation effects of the aluminum. Had they raised the compression of the alum heads to have equal fuel requirements as the iron head, I feel sure that the aluminum head would have outperformed the iron heads.
In your case, your iron heads had been optimised for your combo and 93 octane fuel, so the improvements that the KRE heads have were not enough to fully offset the difference in fuel requirement. You simply needed more compression to exceed the performance of you iron heads. And that would have easily been possible with the aluminum.
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