I bought a Zoli through Navy Arms in 1980 for $125. Yes, It was a .58 with a Minie ball type of rifling. I never shot minies through it, always round ball. It shot well for me. The lock was good, albeit, a flint smasher. Always sparked if you kept a good flint in it. Probably get a dozen or so ignitions and the flint would be bashed quite a bit. But then, flints were cheap back then and I just changed them frequently. Shot a few deer with it. In later 1980s I had Ken Bresien of Warsaw, NY line it to .54 with a 1:48 twist. ($100.)
It was a fantastic shooting rifle.
IN 1993, we had moved to a country home and started to raise horses. So, l sold the gun to buy a horse. (Stupid me, the horse died.) In 2012, I got the itch again for the 1803, contacted the previous buyer, who informed me he had sold it years ago. Where it was, no clue. So I built one from Pecatonica parts with Colerain barrel and Davis lock. This gun is a shooter.
BUT, in 2012, the parts for the 1803 from Pecatonica was $756. And, it was not the easiest build. Love the gun now, great deer gun. Shot one a few years back, dropped it in its tracks.
Zolis are fine, I probably would try to get a .54 but then I do like to be a bit more HC.