I recently picked up a set of older GTP ported heads. The casting number on the heads is 148. Inside the head around the rocker area the only number there is L157. The back of the heads have BCCHCC-09 and BCCHCC-10 engraved in them maybe from the porter but definaly doesnt look like it was from the factory like that. I have searched everywhere that I can think of but havent been able to find out what heads these were orginally off of. Anyone have any clue? Thanks.