I also breached this same subject last year when I decided to raise Turkey's. I did as you are doing and came on here to find the answer, This is what I learned.
Chickens are born with the organism that causes blackhead disease in turkeys, it does not harm the chickens at all, but can readily be contracted by turkeys through feces ( chicken poop ). Many people have posted and said, hey!! I house my turkeys with my chickens without any ill effects, But many more have said that they do not because of blackhead. I built a seperate area just off my chicken coop & run they could see each other but no contact, so it was easy to feed and care for them.
I did not have any problems at all with this set-up, and both did just great, I thought better safe than sorry, I just think that with blackhead disease that it would be irresponsible to just discount the findings and house them together anyway. Some say that it is just carried by chickens, and you have to have the ground soil tested, but they say it gets contaminated from the chicken poop in the first place. Some have free range chickens and turkeys forage together and say they have not had a problem ( YET ).
The moral of the story, do what you think is best for you, but do your homework, in my case I did not want to have raised these fine birds to big size and be ready to process only to have them fall ill and croak right before the time was right. what a waste that would be.
Good luck with your Turkeys and your housing choice.
AL