I'm no expert by any stretch of the imagination, but here's my unschooled opinion, for what it's worth:
you have, I think, a Southern Mountain rifle which was made from a parts kit. the stock appears similar to the precarved stocks offered by Track of the Wolf. these are (if memory serves) made for Track by the folks at Pecatonica. They are well made stocks, and if you need a precarve, I wouldn't hesitate to contact them. I've used several and had good result. the lock is a Durs Egg - I have one on my Southern Mountain and I'm quite happy with it. the furniture looks to come from Track, so there's a pretty fair chance that this is one of their kits (I hesitate to say 'kit' because what you get is a parts set: building one of these guys is
not a tab A into slot B affair.)
had it been my rifle, I would have taken more wood away, but what you have is a good and serviceable gun and you can expect many years (that would be, say, the remainder of your life and that of your heirs) of good service if the rifle is properly cared for. always clean it as soon as possible after firing.
more thoughts:
the front sight is not to my liking - were it my gun, I would change this.
you should assemble a basic kit (assuming that you want to keep the gun) some spare flints, some flint leathers, some powder (probably FFFg, but many .54 rifles like FFg - you'll have to see which granulation this particular gun likes) an adjustable measure (NEVER pour powder from the can or the horn into the barrel directly - very dangerous!) ... of course, some roundball and some patching material ... some lube ... some targets and a stapler (can't count the number of times I've lent my stapler to another shooter, nor would I admit the much greater number of times I've had to borrow a stapler from someone else) ... for the best accessory available, I would point you to Dutch Schoultz' method. His web site is here [see link, below], and it's my opinion that anyone who doesn't have a copy of his work is missing out on a really great thing. (not that you can't figure out what he tells you for yourself, but you'll spend thousands of dollars worth of powder and shot, and a ton of time doing so.) here's a link:
http://www.blackpowderrifleaccuracy.com/
the builder, unless the work is signed or marked, or you have some sort of provenance, would be very difficult to determine in a rifle of this nature. as regards the value, this is a
very slippery thing ... you should check out the Track of the Wolf website, as well as some of the auction sites. you will see that prices vary widely (a 'name' maker will provide a better product, and thus a more expensive rifle) ... be dispassionate and brutally honest with yourself ... if you have any emotional investment (such as, if you made the rifle, or if it belonged to beloved Uncle Harry, now deceased) well, you might be well advised to forego the money thing and just enjoy the rifle, since disappointment is virtually inevitable. (everyone has a Stradivarius in their attic) ...
there you go: free advice, and no doubt well worth the cost
good luck with your project, and
Make Good Smoke :grin: