Bench the gun and only change one factor at a time. Shoot first to get the smallest group for that barrel. Then, and only then, change the sights to bring POI to POA.
If you don't have it, invest $20.00 in Dutch Schoultz' Black Powder Rifle Accuracy System.
http://www.blackpowderrifleaccuracy.com/
It will teach you how to read your patches to tell what is going on with your barrel.
I would recommend you use CAST pure lead Round balls, and Not the Swaged RBs available from Hornady, or Speer. The Swaged balls have antimony, making the lead harder, and much less likely to upset in the barrel quickly when fired.
Try both 3Fg and 2Fg to see which your rifle likes the best. The gun, and your spent patches will tell you.
Recognize that if you use 3Fg with large powder charges( over 70 grains) you may find the patch burning in the center. Try using a thicker patch- .020", instead of the .018", so that it will hold more lube in the fabric. That is often all that is needed to stop the burning. If it doesn't stop the burning, then consider using either an OP wad, or some kind of filler, like corn meal, to act as a "firewall" between the powder and the PRB.
You should be in the ball park using a load of 80 grains of 3Fg powder and that .530" ball, with a .020" patch well lubed. OR, using 90 grain of 2Fg powder with a .530" ball and the .020" patch well lubed, for a hunting load good to 100 yds.