RE: buckshot and choke selection?
First, I will recommend that you get some butcher paper and set it up at 40 yards to see what really works for you. Then, I will say, buckshot works best with cylinder bore. Go to IC if you have to. It is not like a tall column of small birdshot that takes to shaping. The more choke, the more stringers you will get with buckshot.
But do your own test.