It's simple if it's pass shooting for sea ducks, you will have to find what load patterns well in what choke. Yup 40 yards and sheets of cardboard(or similar) and pound away at a different sheet evey time, you'll be amazed what brand differences make, and what the different chokes will do. Same thing for the 5's.
For pass shooting look for as many pellets in a 30" circle at 40yds.
As for the lead if it's closer stuff look for the mumber of pellets in a 30" circle at 30yds.
This is one of those you'll have to experiment with various loads chokes etc.etc. kinda thing, no pat answers, for this stuff, every shotgun is an entity unto it's self.