Here in the Northeast I know of two breeders, both of whom have a lot of Kirschental lines in their pedigrees. The first is Traumhoff. The breeder works her dogs in herding and has been focusing on preserving the GSD as a herding dog. She also obtained a number of dogs from the Kirschental kennels before they shut down. When I was looking for my puppy, I exchanged a number of e-mails with the breeder and definitely liked her, although I ended up getting a dog from Olympia Kennels, which is the second breeder I'd suggest you contact.
Olympia is located in New Hampshire and run by Mike Pinkstein, who used to do a lot of Schutzhund and is probably as well, if not better known as a trainer rather than a breeder. Olympia also has Kirschental dogs in their lines. I liked this breeder and kennel enough to get a puppy from them, although I haven't actually gotten the puppy yet - they won't be 8 weeks old until the end of May. I did meet both the parents and a puppy from a prior breeding of my puppy's parents. Obviously I liked the dogs a lot, since I decided to get one of their puppies.
One thing you should be aware of - both Traumhoff and Olympia (as well as Kirschental) breed what would be considered German Show Line dogs - although they all do have a herding background. From my observation, I would say that these dogs lack the hardness and the over the top prey drive of some of the working dogs, but are very bidable and handler sensitive. They will also tend to be black and tan or black and red in coloring (like most GSL dogs) rather than the darker sable of the working line dogs.
Hope this helps.