I have a copy of the book "The Life of Billy Dixon" written by Olive K. Dixon, but it's been several years since I've last looked at it.
A few minutes ago, prompted by seeing this, I did go pick it up and browse through it briefly.
What I noticed were a few passages in which Dixon describes using Sharps Rifles, both his own and some "borrowed".
He mentions losing his when his wagon got washed away crossing the Canadian River just prior to the Adobe Walls Battle.
In one instance he refers to using a "Round Barrelled Sharps" loaned to him that would have been the ecconomy "Business Rifle".
Apparently his Buffalo Hunting was done mostly during the period when both the .44 (.44-77) and the "Big 50" (.50-2-1/2") caliber Sharps were in vogue. This would have been a couple of years before Sharps brought out the .45-110
To my mind there's no doubt that Dixon was foremost a Rifleman.
I didn't see any mention of any Springfield Trapdoors, although that was a common rifle in those days and there's nothing to say that he might not have owned one at sometime in his life. The special ordered "Officer's Model" was a desireable lightweight .45-70 rifle that served well for Big Game hunting where only a few shots were needed.
I didn't find any reference to him using or carrying revolvers, again, that doesn't mean that he didn't, just that I didn't find any reference to it in the index.
As far as your clothing is concerned, for "Town Clothes" it looks like that coat and trousers you show have it nailed although I'd agree that he's wearing a lighter colored pair of trousers in the photo.
As far as hats are concerned most Buffalo Hunters were out just prior to Stetson's introduction of the "Boss of the Plains" hat that became referred to and famous as a "Cowboy Hat". From images and drawings I've seen they generally wore somewhat of a wool slouch hat, which I believe was common amongst many Confederate troops during the Civil War? Their hats typically looked somewhat like these
http://www.clearwaterhats.com/civilwar1.htmhttp://www.clearwaterhats.com/oldwest4.htmhttp://www.clearwaterhats.com/oldwest1.htm During the winter hunting months, wearing a "Trooper" style fur hat would probably have been common, possibly made out of Beaver.
Clothing would have probably consisted of tan "Duckins" for trousers and maybe similar styled trousers made of Wool during the winter, tall boots coming up just below the knee with "squarish" toes, not really heavy square toed nor pointy as are modern cowboy boots. A muslin shirt, often of the pullover variety was commonly worn. This would have all be worn with wool longjohns on underneath in the winter time when out hunting. It would have all been topped off with a heavy wool or possibly a Buffalo Robe coat for warmth, similar to these.
http://www.millvalleyleather.com/Mens-Buffalo-Fur-Coats_c_9.html (you'll notice the price has gone UP on these!
)
IF a hunter were to carry a revolver, it would most likely be a Colt Conversion or '72 Open Top, it would have been carried in a holster similar to many of the earlier styles seen here.
http://www.oldwestreproductions.com/_System/_DeluxeStore/ProductList.asp?Category=Old+West+HolstersFrom what I know of this, this would probably be a pretty accurate description of what "typical" Buffalo Hunters would have worn.