Check out the Seth Kinman rifle. It was carried by this frontiersman who was a professional hunter.Then its not a trade gun . If you want to build a percussion rifle and put a dragon side plate on it ....go for it !
The rifle was restocked and belongs to no school. It was a one of a kind gun.
Seen today it looks like a Disney movie gun and nothing like a ‘real’ ml from the time.
Guess what?
People repaired and replaced stocks. And made guns from miss matched parts.
Your gun won’t be historic in the way it would have fit in with typical guns of the time. However no less authenticity styled, as your one of a kind did not exist, such one of a kinds did exist.