If you do a search in the turkey section I suspect you'll see this question answered several times over, but...
I believe chokes are second only to camo in the degree to which they are hyped. People pay fantastic money for a small round piece of steel that is no different than any other small round piece of steel with the same dimentions. Chokes are chokes... the theory that shotguns perform better with different loads and combinations is brought over from reloading rifle shooters. It simply isn't that complicated. Get a tight choke, get a good 2 oz load, and go kill a turkey. I've used the one that came with my 870 turkey special for years without issue. I've used the regular full that came with my SBE II without issue. I've even (gasp) killed turkeys with fixed choke model 12s in Modified and Full.
Not long ago someone posted pictures of the various loads they'd patterned. It showed (here's a big surprise) that the load with the most shot in it had the best pattern! Wow, right? Then a pattern with bigger shot and a smaller payload had a less dense pattern. Who woulda guessed?
I'll save you the time, get a box of 3 1/2 5s or 6s, preferably the 2 oz loads, and a full choke. Any additional free time you have, spend it scouting.