Pat,
I think I follow the twisted logic as explained in the Team Camaro thread
The engine is coming out and staying locally before the car goes to MO, so I will have relatively easy access to check out casting numbers, dates, and any stampings. I will also look for anything stamped on the starter mounting flange - first time I've heard of that, but interesting. I'm pretty confident there are no other characters stamped on the pad in front of the cyl head. It may take a few weeks, but will check it out.