Here is my take on the subject.
You can't take too much gun on a pheasant hunt
Been chasing them for 20+ years in Grant and Kay county, and I've always filled up one side of my vest with magnum loads of 12 ga #5 or 4 shot. 2 3/4 or 3", whatever your gun will shoot. The other side is with magnum loads of 7 1/2 or 8 shot. ( I reload both) If a covey of quail gets up take what you can, and then switch to the 7 1/2's to hunt the singles.
For chokes, I go against what all the "gunwriter experts" say. I use an improved cylinder in the top barrel, or right side depending on which shotgun goes with me, and a modified choke in the bottom or left side. For a single barrel, I'd use an improved or modified with the magnum loads.
Here is my personal formula: Spending the bucks on premium loads for a limit of birds = sucess vs wounding and losing a bird. You only have a limit of two birds so, buy turkey loads or whatever and get your birds. A load of # 5's at 1 1/8oz loads pales in comparison to a load of 1 5/8oz in the pattern. I have dogs, and hunt with people that have dogs, and get tired of seeing a huge puff of feathers come off the bird and then spending a half an hour looking for a running cripple and not getting a recovery due to dry conditions, etc. They are a tough bird and really hate watching the "hunting shows" where they put out planted birds and brag about how they can use a .410 to kill them to impress people about how great a hunter they are.
Yep, it only takes one pellet to kill them, but the more pellets you can get in them, the better your sucess.