After trading a few more messages, the heads I asked about are stock ZZ4 heads, 10088113. In their "Five Stage ZZ4 Build" ( Link - Small-Block Chevy 5 Stage Build - Popular Hot Rodding Magazine ) they changed out the stamped steel rockers for a mix of Comp Cams rollers (1.52 exhaust, 1.6 intake) and pushrods, then started in with intake, various cams, and finally in Stage 4 they tossed the stock aluminum heads in favor of a pair of RHS cast-iron Pro Action heads,
64cc chamber, 180cc runner PN 12318-05. While I'm sure they flow better, I really have a hard time swapping from aluminum heads to cast iron. Wouldn't it be better to swap to a pair of aluminum heads with the larger 2.02/1.6 valves and improved flow as opposed to cast iron? Stepping back to iron heads for the street seems like a step backwards to me.