All the 45 CVA Kentucky rifles (with two piece stocks) I have seen or owned had 1-66 round ball twist barrels. You may want to try a LEE REAL bullet, as some have had success with it. Other than that believe a patched round ball is your best choice. Figure 75 yards or so as your max range for a broadside lung shot. Others may suggest 100 yards. Many deer have been taken with a 45 caliber round ball throughout history. Nothing wrong with it if you remain a hunter and not just a shooter. I would start with 50 grain charge of fff (or ff if that is what you have) and increase until accuracy goes away, then back off 5 to 10 grains for your ‘accurate’ hunting load. I use ‘real’ backpowder and prefer Swiss.
Good luck.