Which head/combustion chamber is better for performance? Speed master aluminum LA or aftermarket magnum iron head?

pittsburghracer said

There are some pretty nice magnum heads out there but the trouble is they came on Mopar crate engines or other sources and are no longer available.

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Which head is that? Most of the crate engines I’m aware of used either;

Cast iron magnum head
Cast iron magnum R/T head
Aluminum edlebrock magnum head