Amstaff, what is the huge worry with HD? Did one of your dogs turn up with it and now you are super worried? Nothing wrong with being informed and knowledgeable on the subject, but I was just wondering.
My advice, whether you choose breeder or rescue, is to pick a dog that has a normal gait and no stiffness or soreness or reluctance to play. Keep the dog in good muscle tone and at a good weight. HD is bad, but its not the end of the world, and its most certainly not the only thing that can happen.
God luck!