They look fantastic, and those are very good qualities to be combining in a breed. How many hens and roosters did you start with to get those 27? Line breeding is the only manner I know of to get a closed flock to last, but that wouldn't do much for stabilizing genetics. After 6 years, I'd expect some inbreeding problems to show.
There's a hole in the bucket, dear Liza, dear Liza, a hole in the bucket, dear liza, a tiny ad:
it's easier and more soul building than any workee-job