Jeff, Tom Roebuck in Virginia would be the guy you want to talk to about Buff Rocks. They are very rare especially quality ones. Tom has been working on them for a year or two and I seen his birds at Crossroads and I was impressed. I'm sure he will tell you that they need more work but I...
Britrock, the bird in the picture you chose is not in full feather...you may want to look around some for an American bird in full plumage to compare to your Rocks. I think you would have a better idea of how an American Rock and your Rock compare if you done so. There are plenty of pictures...