I'm sure the OHC 6 is fun to drive, but I bet putting your foot into a nicely built 428 will be even "funner".
The "world" isn't going to offer you anymore for a pristine numbers matching OHC 6, sure a few here might but I didn't see anyone making you any offers for it either, so it's just "in theory"...
So if "in theory" the OHC 6 is rare and that valuable, all of us would be off the charts since our cars were actually the upgrade to the Camaro and few were sold in comparrison. But "in reality" we seem condemded to being the step child of the Camaro (and GTO for that matter).
I vote to build that car/428 for all you got! Good luck!!