It was done to legalize the heads and valve-train configuration for trans am road racing.
Actual race heads seem to be even difference castings that T/A passenger car heads. But have same casting numbers .
Boss 302’s weren’t anything that great on the street with their big valves and small CID. And I don’t think Boss 302’s made/make successful NHRA class racers either.
BUT the Boss 302 won the 1970 Trans Am championship.... that was the objective.