Have you found out anything yet? If chickens are anything like goats then a pairing like that would work for a generation or two. It seems the likelihood of having to cull for health issues would be higher though.
Seabrights originally were bred in England and are the only breed that has only one size.
Wyandottes were originally bred in Wisconsin, USA. They now can be found as large fowl and as bantams.
As for similarities in appearance, I will be able to see that for myself soon. I already have...