Maybe I'll just bite the bullet and pay for a letter from the factory. Might tell me something.
Do it! A piece of history like that should have it's back history in order. Even if it turns out to be not too remarkable it sure would be nice to have it's 'official' pedigree available when you take it to the range or show it off to your friends and relatives. Probably a son, daughter, niece or nephew that might be nicer to you once you show it to them.
It's definitely a handsome pistol! I'd have jumped on it at that price too.
Pardon me for asking but did we ever establish if it was a .45 ACP or a .45 Colt (sometimes referred to as a '.45 Long Colt')?