Looks like a silver seebrite. Some have a single comb, just a poor quality one, as far as breeding and showing goes. As for a chicken, he sure is a pretty one. And he seems good natured.
I agree, everything but the comb says sebright to me, the nankin was used in developing these chickens and it can have either comb, my guess is it's a throwback gene somewhere in breeding.
it looks just like my silver seabrights except for the comb, the girls hardly have a comb and the boys have a big fat solid comb not sure what its called though.