I own three Sharps rifles, a Pedersoli 1874 rifle in .45-70, a Shiloh Sharps 1874 rifle in .45-120 and an antique 1863 Sharps carbine that was converted by the US Government to .50-70 in the late 1860s. I have shot all three.
The Pedersoli rifles are excellent in my experience. Although the fit and finish on the Shiloh is definitely nicer, I wouldn’t compare it to the vast difference between a Norinco firearm and something else like a Colt or Kimber etc... the difference I’d argue is closer than that. Further, the barrel quality on the Pedersoli is also excellent, and it is capable of very good accuracy. I haven’t compared my Shiloh to my Pedersoli given the different nature of the two rifle calibers, but I’m very confident in the accuracy of the Pedersoli.
If this is your first foray into BPCR shooting, I’d personally recommend a Pedersoli in .45-70. Not only is the rifle cheaper, but a common caliber will make life so much easier in many ways. I have a very hard time finding .45-120 brass while .45-70 brass is plentiful and (relatively) cheap. The extra money you save in buying a Pedersoli will pay dividends when used for ammo, powder and range time.