YES!! I've found dorkings!! Albeit of the single comb variety, but I still may add them in! Found Orphintons too...
This is what I would use each breed for, if I use it.
Sex-links - high production, good feed to egg conversion ratio, winter laying, easy to tell pullets from cockerals
Barred Rocks - supposed high egg production, pattern, hens used to create red sex-links
Wyandottes - LOTS of feathers, small comb, wide body, pattern
RIR - supposed high production, roosters used to create red- and black-sex links
NHR - supposed high production, roosters used to create red- and black-sex links
Delawares - supposed good production, wide bodies, hens used to create red sex-links
Buckeyes - small comb, winter layers, supposed good production, roosters can be used to create red and black sex-links
Australorps - good temperament, supposed high production, wide body
Chantclairs - small comb, winter layers, supposed good production
Icelandics - coloring, supposed wide range of climate tolerance, supposed broodiness (I know I most likely wont get a high production broody hen, but a girl can dream)
Marraduna Basque - coloring, excellent foragers, supposed decent production, body shape
Leghorns - body shape, supposed high production
Dorking - supposed good layers, coloring
Orphington - supposed good production, wide bodies, LOTS of feathers
I'll draw a picture and post it, and tell me if you think it's possible to create with these.