ADK
I assume it is unchoked? The truth is, only you can determine how your shotgun will perform with any load, shot or ball. The fun is in the experimenting. Chances are, you will have one barrel that will shoot fairly close to point of aim with a ball, but it will be unusual for both of them to.
Shot loads? I use 70 or 80 grains of 777, an overpowder wad, a thin cusion wad (I quarter the whole cushion wad into 4 equal wads,) 1 and 1/4 oz of shot (I like #6) and an over the shot card. Some people just load the shot on top of two overpowder wads and skip the cusion wad.
You can play with your loads and find out what works best. If you have one barrel that throws a pattern low, you can adjust that by either increasing the amount of shot in that barrel, or decreasing the amount of powder. I know that seems like a hassle, but it works to a point.
Dan