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Late '86 corvettes (all convertibles, and I forget the coupe VIN that began it) had aluminum heads.
The aluminum heads had 1.94 intake valves and 1.5 exhaust valves. They were a 58cc chamber. Quickly identified on an L98 Corvette by the centerbolt valve covers as the irons had perimeter bolts.
I don't know the info for the iron heads besides having a larger chamber.