Rick,
It's hard to tell anything from the pictures, but I'd guess that it is in fact an old original gun simply because the barrel looks to have been cut back from the breech end, judging by the placement of the rear sight. Then matching that thought, the forearm seems to have only two RR thimbles, instead of the usual three, and the thimble closest to the muzzle is too far back from the muzzle, so originally there would have been three thimbles on the stock.
To me that says the gun had the barrel cut back and the forearm cut back at the same time, so the gun isn't likely to have recently been made from parts.
However, on a gun like this with no patchbox, etc, inexpensive is a definite plus, and must!
By the way, I agree with you on it being an original percussion.
John