I also have an A5 stalker with a 22 inch barrel and synthetic stocks. I picked it up used spur of the moment last week. It will only shoot 2-3/4 inch shells though.
I would go with this one the A5 Stalker
You can still get the 2 3/4 turkey loads
And I would try #6's
For two reasons you get more shot and the smaller the pellets,
The less it will deform when going down the barrel and out the choke.
The thing is I was doing some checking and some of the pheasant loads are pretty stout. I currently have some federals that have 1-3/8 oz of #5 shot in 2-3/4 inchers for my A5 and they will do 1350 fps. And I looked at a shot size chart and by dropping one size in shot (4's to 5's) I get almost the same amount of pellets, just not the same amount of weight. And I have seen some that will get up to around 1500 fps.
Pheasant loads #5 shot in 2-3/4 inchers will probbly do ok
After All Dead is Dead regaurdeless of what shells and shot you use.
JMHO
What ever you be carefull and remember to use ear plugs
Good Luck