Generally speaking the 461s--if you have them--were the original 375hp "Fuelie" heads, replaced by 462s in 1966. Not correct for a '67 Camaro, but the guy with the Rat knows something. Does he have a 'Vette? chuckle. These days, just the sight of a set of "double-hump" heads makes the adrenaline rush because they have become so rare. If there is an "X" in the casting # you have a rare set indeed, with bigger ports.