Can someone tell me what I have please. Hoping to use these for my 455. Edelbrock Aluminum heads labeled 6506. Picked them up for $500, machine shop said they were not cracked, and good to go. Person I got them from could not use them. I think they are the 87cc version of the Performer RPM.

 

They look like 72 cc to me. The 87 cc casting has a partially machined chamber.