I have one that is about the same vintage. My bucksinning business sold it back in the late eighties, or early nineties, to a friend. When he passed away, his wife gave it to me, for helping her dispose of his blackpowder stuff. It has had nothing done to the lock other than polishing to inside, and outside. It shoots as good as any production trade gun I've ever shot, and better than some. Polish it up and shoot it.
Hungry Horse