You need to put your deposit in at Shiloh for a Mt Rough Rider in 45-70 with a 30 inch heavy half barrel. You can kill an elk at 200 yards "with practice" and with the proper load a 1000 yards target shooting is totally possible. Other calibers are also available but the big cases such 45-90, 45-100, 45-110, 50-90 all should be shot with black powder due to the large case capacity. Some guys get by with smokeless with certain powders, but the recoil and pressures can be high. Shiloh recommends only factory produced ammo if you're going the smokeless route such as the 45-70.
I have 4 Shiloh's, one in 40-65, 2 45-70's and 1 45-100. In 2016 I Shot at the Nationals at the Whittington Center in Raton. In the Creedmoor match I won the top scope class. I used my Mt. R.R. in 45-70 topped with a MVA 6x scope.
Other brands of Sharps can shoot good, but they will not come close to the quality of a Shiloh Sharps. The old saying "buy once cry once" really applies in this case. No matter what brand you buy the 45-70 is the best choice.