I knew a guy years ago that traded in original Sharps rifles from the buffalo period. He had dozens of them over time. He'd shoot most of them, at least a few rounds each. Those that he kept a while we'd shoot fairly often. They were a lot of fun to shoot.
Seems like most of the old buffalo guns I've seen weren't the fancy grade guns that I've seen from the modern makers, but fairly plain guns with heavy barrels, many built on Civil War percussion carbine receivers converted to cartridge. One reason for the heavy barrel guns was to soak up the recoil from shooting a lot. It makes sense from that perspective, buffalo hunting as a market proposition entailed a fair amount of shooting on a regular basis. At first I didnt take to them, but I came to like the "Business Rifle", which was a medium heavy, round barreled rifle, put out as a regular production model for general sale. It did alright for buffalo, and was lighter to carry than the heavier octagon barreled guns. The carry aspect didn't matter as much to the buffalo hunters, their horses and wagons carried their guns for the most part, but I believe the Business Rifle model was fairly popular. My use would be general shooting, and some dragging it around in the hills and mountains. With that in mind, If I were to get a Sharps now, I'd likely go for a Business Rifle. I'd add double set triggers, a decent tang sight and sling mounts and be pretty happy. I could work with either a 45-70 or 50-70. 50-70 would be fun for the historical factor. 44-77 would also be interesting, being one of the earlier calibers.