Thank you all! When I bought the gun, it was sold as Day's; admittedly, I am not particular who made it, as I really just wanted a swivel breech, and this was the most economic option towards acquiring one. For now, it's a project gun, and I suppose my options are fairly wide, so long as the tang and breech ends mate with the swivel.
Still debating if I want to do a double rifle, or one rifled one smooth.