i agree with the "southern" assessment, despite not having much to go on. The gun has straight comb and toe lines despite a worn toe that makes it look a little "curved" in that area. That, and the extended square shank on the percussion drum or side lug, suggest a southern gun. It's a rather late gun without a cheekpiece, which helps explain the re-use of an earlier barrel, perhaps more than once from all the scars it exhibits.
If you decide to re-assemble the gun, I suggest mounting it completely in iron, since you have one original iron ramrod pipe. On many "mixed metal" southern guns I've seen, most have major mountings, i.e. butt plate and guard, in hand-forged iron, and the smaller pieces such as ramrod pipes and nose cap made from sheet brass that's easy to work. Since your rifle already has one iron pipe, it suggests to me that it was probably completely iron mounted.
I always thought mixed-metal mounts [iron & brass] were often due to a lack of casting skills in later gunsmiths, but most could fabricate an iron butt plate or guard rather easily, then use easy-to-work sheet brass for the smaller pipes and nose cap to give the gun a little "sparkle."
Some of these relic or parts-rifles have so completely lost their original identity that, if rebuilt, they still have little value. I can understand wanting to put it in a more presentable condition, but you may want to think about how much time and money you really want to invest in it, since while increasing its value, this one will probably have limited value after restoration.
Shelby Gallien