I used to work for a turkey processor. Occasionally, they'd process a group of "breeder" turkeys (the ones they actually use to produce the production lots of birds, which commercially are usually 12 - 14 weeks old at slaughter). Anyway, some of those breeders would top 90 pounds.
I kid you not.
But once the birds got that big --- at least for commercial processing purposes --- they would just part them out and turn them into other products like bologna and hot dogs.
What I would do with a large bird is hot smoke it, very slowly. The hot smoking tends to heat more evenly than any other method, plus it adds a good flavor. Furthermore, if you're really concerned about fully cooking the bird - or you just want to cook it faster -- then you can take hot coals from the grille of the smoker, wrap them in several layers of aluminum foil, and stuff them inside the cavity of the bird. That will cook it lots faster, but you need to be pretty dextrous with utensils.
I kid you not.
But once the birds got that big --- at least for commercial processing purposes --- they would just part them out and turn them into other products like bologna and hot dogs.
What I would do with a large bird is hot smoke it, very slowly. The hot smoking tends to heat more evenly than any other method, plus it adds a good flavor. Furthermore, if you're really concerned about fully cooking the bird - or you just want to cook it faster -- then you can take hot coals from the grille of the smoker, wrap them in several layers of aluminum foil, and stuff them inside the cavity of the bird. That will cook it lots faster, but you need to be pretty dextrous with utensils.