Very original, with the exception of the sight. Golcher locks were commercial hardware locks, that smiths would catalog order. I would guess it was built between 1845 to 1875, just before or after the war of Northern Aggression. Western Pa. or Ohio built. It may have been a commercial made hardware store gun. It's in fairly nice shape, not high value but still should not be cleaned beyond a wipe down with a damp rag with a little murphy's. Over clean it and it becomes a $100 gun. Underside of the barrel, may have a makers name, and I wouldn't be surprised if it said Remington, as he made barrels for the gunsmiths trade, long before he made guns himself.
Bill