whitney- whitney kennedy ???
Can't be a Whitney of any flavor. Their frame curves down to the root of the lever - semi Marlin like but different. That would be easily observable in this photo.
I'm convinced it is a Bullard. However, there is and interesting pin or bolt midway in side of the fore arm. That is pretty odd. The entire forearm looks odd and unlike anything that I know of. Perhaps it is a home-brew, Bubba half mag adaptation.
Whether the guy owns the horse, rifle, or pelts, it is still an interesting rifle and an interesting, if odd, photo.