If you're a good enough shot, the head would be the primary target.
Otherwise, if a turkey is standing crosswise to you, shoot the butt out of him. A main-body shot is a waste, as that bullet will blow up and ruin the breast...Yuck.
If you handload, use a quality bullet and load down to around 1,500-1,800 ft/sec. The bullet won't expand and ruin meat.
You could consider having your shotgun muzzle threaded for screw-in chokes. Then, use the new "turkey choke" which folks are raving about. It's "ultra full".
FWIW, Art