My question is what part of this project is Southern mountain? Not the lock. Not the stock ( at least from the styling you mentioned). And not most of the furniture. The only part of this project that might be construed as "Southern mountain" is the trigggerguard. I would also think a buttcap on a salvaged parts gun, from the region you suggest, during a war, would be unlikely. A French, or English, style lock would lend the project more credibility. I would also consider a barrel made to look like a damaged musket, or officers fusil barrel, shortened to pistol length. Side plates in pistol size would be an unlikely find, consider a hand made one, or just washers.
Hungry Horse