First off welcome Jake, I would say you just need to buy a few different turkey loads and shoot them and see what kind of pattern you get and what works best in your set up. Clark Bush has years of research to his credit you can check out his web site at http://www.allaboutshooting.com/
and get some really helpful information. I would say starting out you can pick up some 3" 2 oz # 4, 5 or 6 lead or copper plated lead shot. Its relatively inexpensive compared to the Heavier than Lead loads out there. I would maybe start with some of the Winchester loads that you can pick up at Wal-Mart or your local sporting goods store and see what they do and go from there. Let us know how it dose and any more questions you have post them up and well try and help.