You can decide if you want to reload with .264 bullets and stay on the safe side (if the bore is a tad dark but the rifling strong, also the accuracy might be more than ok. I shot quite a few Norma rounds in my Carcano, and they are loaded with .264 bullets.
Or you can use the .268 bullets. But the gain twist barrel causes some headaches sometimes. A wrong powder could cause the pressure to go up. Look for good reloading data if you can.
For what matters, I use 37,0 grs of W760 and a MLR primer and the results are great. Just too bad that powder is unobtanium here...
I don't know if you have it there, but there is another powder used by lots of Carcano shooters, the Tubal 5000. I don't have the reloading data in my head, but I have a reloading manual with them in. If you want, just let me know here or per PM.

Enjoy the little Italianicon rascal!