Talked to pops tonight about his buddies Camaro. It was a '69 396/375 that they replaced under warranty, after a month or two, with a L72. So, unfortunately it wasn't sold as such. It does seem this may have been his buddies plan all along as dad says "There was nothing wrong with that engine."
If you couldn't get it from the factory get it under warranty. (They didn't know about the COPO's unfortunately)
They did the same thing with another good friends '69 396/375 Nova.
Both of them claimed their engines used excessive amounts of oil.
While neither may be "real" cars, I'd love to find either.