An old topic, but after several years of marketing "heritage" poultry meat, I realize that a critical point was missed in my previous posts (bcbreeder). Cooking must be low and slow, we often roast at between 300 and 350'F. We roast until the meat pulls from the bones. This is critical. The old fashioned leg test, pull the leg and if it pulls back, the bird is still going to be tough. If it feels like you can pull the leg bone right out of the bird, you now have a juicy flavourful bird.

Here is a link to an information sheet I give my meat customers.
APA Grand Master of Bronze Turkey, Black Ameraucana, Black Muscovy, & Khaki Campbell