The blocks and heads were REQUIRED to have a factory stamped part number for use in Pro Stock, unless that has changed in the very very recent past. The stuff I had all had Mopar part numbers in the head and on the block. My car also has Mopar part numbers on the entire thing, body, trunk, doors, dash etc. Don't mean much as they submit the parts for NHRA approval and once given they are produced. Same thing happened with the Eicke stuff. The were not the direct Pontiac parts, they casting was changed to make them have a Siamesed exhaust port like a factory head. Just as the latest "Hemi" run in Pro Stock is not a Hemi...

As for the comment is the current Pro Stock internals were laid out on a table I doubt most anyone here could identify them unless they had seen them previously. Age would mean nothing.