SoCal appraisals/does this increase or decrease the value of my 1876

[Collector0311]

I have an 1876 (1894 production year) chambered in .40-60 with what appears to be some type of native tack work done on both sides of the stock. The work is beautiful and patina on the brass tacks looks to be of considerable age. Is there any way to verify age or authenticity of the tack work? Also the forward barrel band was replaced by silver solder (again looks very old) but I have a replacement band for it. Any advice as to how/what to do to find out the value or even increase the value of this rifle? I am located in SoCal and am looking for an honest appraisal. Is the cost of the Cody letter worth it? Other important info: Serial number 42688, dust cover, lever lock, butt stock trap door all in tact, all wood without cracks. Ultimately looking for a fair price to ask for this piece. Thanks in advance for any help gentlemen.

(edited to add pictures and other pertinent information)

 

[Onmilo]

Tacks sold through Indian traders and agencies were all square brass shanked well up into the 1920s.
Modern upholstery tacks all use round steel shanks.
Pull a tack from an unpronounced area and you will know,,,

Without a letter of authenticity from the Native family through which the gun was passed own, verifying "Genuine" Indian use firearms is a very shaky business.

The gun will still sell based on the antique condition standards set for all old Winchesters and the guns in shootable condition still realize quite decent prices without adding any suspect histories to them. HTH

 

[jim in Anchorage]

Hurts value same as someone carving their name in the stock.

 

[Collector0311]

What about the other aspects of the rifle? How does the quality look to any of you who have seen these before? It will still shoot pretty true to about 100m. Also the barrel needs a real good cleaning, looks as though the past few owners have just let it build up. I've never shot cast bullets before now, not to mention black powder loads, so I'm completely ignorant as to the best way to safely and effectively restore the quality of this barrel as much as I can. Any ideas?