I had a Bill Large .58 - would not shoot accurately with anything but what most people would consider to be heavy charges & it excelled when fed correctly.
2F or 3F - you'll have to work up a load with either powder. If you only want to shoot at pellet gun ranges (25 yards), then shoot any load you want, ie: 50gr.
If you want to shoot accurately at 50 to 200yards, you'll need to work up a load, starting with a substancial patch and ball that is only .005" or .010"(at the smallest) smaller than the bore. You'll need to learn to load it using a short starter. I'd start at a minimum of about 85gr. of 3f and 100gr. of 2F and go from there in 5 gr. inciments until I found a load that shot well enough at 50yards, then test that at 100 or further.
Even my .45 demands 75gr. of 3F or 85gr. of 2F for accuracy shooting when using an oiled patch. Anything less is innacurate, however, at 25 yards any load will stack the balls on top of the other off a rest - with every one of my rifles and my smoothbore too.
I suggest you borrow Lyman's BP handbooks along with Ned Robert's "The Muzzleloading CapLockRifle" and study them. They will help you a lot. Lyman's books will teach you about using a patch that goes beyond the bottom of the grooves when wrapped around a ball, ie; ball diameter + 2 thicknesses of patch, equals LARGER by a few thousandths over the groove to groove measurment. If it does not, it will not shoot cleanly and you'll have to wipe it out often. This results in a changing bore condition shot to shot, which is detrimental to accuracy due to the inconsistancy of the friction inside the bore.
This picture is from Lyman's excellent book. It shows how the patch should compress into the ball by not only the lands, but the grooves as well, in order to seal, give the best accuracy and shoot cleanly.
A water based lube will shoot well for target, with less powder than an oil-based lube. Good accuracy testing will show this.
Smoothing the crown (emery cloth, or wet and dry paper with tapered V dowel or your thumb) will ease the starting of the patch and ball combination.