You don't really give enough information for a real answer. Are you going to try to keep them in the same housing? Separate housing? How closely will they interact?
Broadly speaking, raising chickens and turkeys in close proximity can lead to Blackhead disease in turkeys (chickens, while susceptible, are resistant but can be carriers and transmit to the turkeys).
If your turkeys and chickens will be sharing close living quarters you could be courting disaster.
That said, I have turkeys and chickens (the chickens live in a coop and free range during the day, the turkeys, while totally allowed to go in the coop, have decided my truck is the better nightly roost - so they don't sleep/poop together) and haven't had a problem - SO FAR. But again, the turkeys don't spend much, if any, time with the chickens and the ranging area is quite large.