You have a Pedersoli, it is not by any means an original.... whatever you do don't make the mistake of treating it as one or you might find yourself getting hurt.
I know several guys who own Armi-sport & Pedersoli Sharps. I would say go no higher than 70 grains FFFG (for the rifle I'm not really sure on the carbine) and make certain your gas check is tight. As soon as it begins to leak replace it. This involves dropping the breach block out and taking it to your local hardware or car parts store for an O ring.
My own suggestion would be to take a look at the NSSA message coard or to the Civil War Guns site and ask what solution men who own one have found.
Believe me when I say the gas leakage issue is serious, I have watched a man put a hanky over the breach and fire his Sharps, it set the hanky on fire.
If you are live firing your carbine I would wish you the best. I know of noone who dislikes their carbine, but all have had to watch that gas check.
The problem is apparently two fold, modern lighter steel and looser fittings than the original. The originals had the problem ( the
CSA manufactured ones by far had it worst), but it showed itself only after a LOT of shooting.
As to a Sharps rifle, I have decided to wait and hope I eventually have the $3k for a Shiloh M1859.
Good Luck & let us know what you find.