My reading on the subject has indicated that most supposed experts consider the Sharps action to be basically a weak not a strong design and that even when made from modern steels it is not for the Marlin or Ruger level loads. Most recommend sticking to original BP level pressures but for sure don't attempt to use Marlin or Ruger level loads in it.
I think the same applies to modern repro rolling block guns as well but apparently not to copies of the Winchester High Wall Falling block gun.