I've only purchased scions for grafting not trees, so I can't provide an recommendation for an orchard. I'm not yet convinced pecans are a good investment for a QDM program. I've seen a lot of conflicting reports on deer use. (Of course if you're planting them to eat they are great!). I'm still experimenting. Here are a couple threads I transferred that you may want to read before decideing to ad them to your program.
Nolin River Nursery is my favorite. I have also purchased persimmon and pawpaw from them. Very nice trees with large roots. I have also purchased from Stark Brothers. Make sure that you order scab resistant varieties.
I ordered a pair of large trees from TyTy Nursery in GA; an Amling and a Cape Fear. Planted them 2 years ago and they took root and are growing...albeit slowly.