Shotshells are loaded by shot weight, not shot size. Any load you have for #8 shot will work with another size, say #2.
#8's for turkey?
Hodgdon and Alliant (and probably others) have load information on lead shot in 3 1/2" hulls in their free loading guides.
Choke? I like a full, but that's just my preference. Works good for me in my shooting circumstances, never had reason to go to anything tighter.