Firstly, you need to check with your state regs to make sure #2 shot is legal. It is not legal in any state that I ever hunted. Fours or smaller only.

Since Nitros are so expensive I only load one Triplex 3.5", 2.25oz' 4X5X7 in the chamber. What is loaded behind it really doesn't matter because if I can't kill him with that there isn't much point in any follow-ups.

On the other hand, I have shot turkeys (pre-Nitro days) that were notcompletely dispatched with the first shot and had to shoot them again. For those shots I would recommend going with smaller, rather than larger, shot because it provides a larger, more dense pattern. A wounded turkey will be moving and hitting them running or flying is no easy task. The more shot the better in my book.