I also have a friend with one of those - what are the odds? Loading him some ammo for it is what resulted in me being set up to load the 50-70. The problem with his is that his rifle's bore wasn't relined during the conversion and is HUGE! I'd have to get a hollow base mold to cast bullets that stood a chance of working, and he didn't want to spend the money for that. I may still do it myself one day just to see if I can get it to shoot something more resembling rifle groups than shotgun patterns!
At any rate, there is definitely something special about the old Sharps. My gun surgeon has an original in 95+% condition, and it is a beauty to behold.