Keep the heavy bullet and start experimenting w/ 60 gr 2F and work your way down. Mine P53 Armi-Sport shot about 6" high and IIRC to the right. A little sight work and experimentation w/ the load... you can have a good shooter.
The NSSA site might be your best bet
www.n-ssa.org as I know many shooters prefer to use a lighter load of approx 40 gr of 3F and attain some outstanding groups at 100 yards.
I prefer to try to keep to the load and bullets the men in the field used. I know I have proved a man at 200 yards would be in serious trouble with anyone who even vaguely knew how to shoot and a 4 x 8' target @ 400 yards... or a formation of men; easy.
As the Italian repops go... I favor my Euroarms M1841; two different shooters a single 3" group at 100' w/ a 60 gr 2F load.
Another acquintance put 5 rounds into one ragged hole w/ his Lodgewood accurized P53 Armi-Sport... but that is no longer a Armi-Sport. Glass bedded, trigger work, sight work, stock lightened etc.