There are a lot of breeds he mentions need work. I found many, and listed a few here. He seems to be really open about what he is doing and why. I think people need to be aware that if they order from Sandhill they are most likely not getting a show quality chicken. Many still need improvement, but he's trying to preserve the breed. Private breeders can build on what he has started if they are seriously interested in showing rare breeds of chickens or just improving a certain breed.
Barnevelder: Please only request these if you are interested in working toward perfecting this breed and you are not interested in showing them at this point as they are not up to show quality yet. This breed, as it stands now, is for the person who wants a calm chicken that lays a deep brown egg.
Buff Catalana (MB): We are still trying to work with them to refine color and conformation.
New Hampshire (AMB): We have selected for production first, and show type second.
Partridge Chantecler (AMB): Still working on improvement of comb type. Body type is good.
Black Dorking (EB): A rare color that, in an effort to save it from drastic inbreeding, I crossed with other colors of Dorkings. We are getting both comb types (rose and single) and, while a predominent number are pure black, some off colors (principally dark gray and birchen) are showing up.