That rifle has the 1-18 twist so you'll get the best accuracy out of it with 500 ish gr bullets. The problem is Pedersoli's chambers can be a bit generously sized, so most likely a .460 diameter bullet will be the best.
Once you've got a bullet like that start with 65 grs of 2f black powder a .030 fiber wad, and seat the bullet to the driving band.
Then you can start assigning values to the marks on the staff, up until the time you shoot a load those marks are pretty meaningless. The load you're shooting and the conditions you're shooting in will assign the values of the "vernier" marks. if you change loads the marks on the sights will change also.
Once you figure out where to set the thing for 100 yds, then you can begin to figure that it'll take about 15 minutes of elevation for every hundred yards beyond that 100 yd zero. But you'll need to keep careful notes of the settings at each distance with each load you shoot and under what conditions you shot under at the time. Temperature and sunlight will play a role here, and not sure which sight you have but the windage adjustment can/will make some difference to the elevation requirements as well.