http://www.montanavintagearms.com/scopes.html
Probably the most usable because it has windage in the rear mount (Front too, for calm air zero.) Shorter tubes than others, sliding recoil mount like a Unertl. Not as frontier looking but not really inauthentic, not all 19th century scopes were the length of the barrel. A friend has one, very nice.
http://www.parsonsscopeservice.com
Only shows scope *repair* you will have to ask if they are still making long tube scopes. I know of one of these in use... in MVA mounts with their windage rear. He was really throwing money at the problem.
http://www.lautard.com/RHO/
Another friend has one of those and it is good glass, maybe better than MVA, but limited in convenience by the front windage.
The Jap brass tube scopes from Pedersoli, Navy, Dixie, et al run from cheap and nasty to quite fair optics. I once saw a 4X Hesco that was not bad at all. But the brass brackets (I won't call them scope mounts.) common to all are terrible. The Hesco was in gunsmith's shop-made mounts that fit some standard block or base and gave a measure of usability but not enough adjustment range for silhouette or midrange target shooting.