Ok, I have owned or own a number of 1858s, from original Remingtons, Pietta and Uberti. The Uberti are long gone. I have also owned a number of Ruger Old Model Army, though I have owned no Ruger New Model Army, and I am just not familiar with that particular model. I have not owned the Pedersoli Remington Pattern Target gun, but I have handled and shot one. If you are looking for a ‘1858 Remington’ looking target gun, the Pedersoli may fill the bill, thought the matted/sandblasted finish on the one I shot looked very contemporary. The owner of the gun claimed, though I never confirmed it, that the Pedersoli was made using an Uberti frame and some Uberti parts would fit (for example, he stated an Uberti cylinder would fit his Pedersoli). The Pedersoli was as accurate as the Pietta Target guns I have shot, and similar accuracy could be said of the Rugers, though a lot depends on who is behind the trigger. For me, the big selling point of the Ruger was its durability. I was shooting SASS and while nothing else made it through more that a few matches without human intervention, the Rugers just kept on going. And going.
I am not an expert by any stretch, but
@45D probably is, and someone who’s opinion should carry some weigh, likely having handled more cap and ball pistols than most anyone else on the forum. I believe he is the owner of Goons Gun Works.
Goons Gun Works Hopefully Mike will check in and offer his opinion.