I also would use George at Gessford. I think you would benefit because he is located in Nebraska, which last time I looked, was considerably closer to Wyoming than Arkansas.
Both Keith and George build great motors, but I lean toward George due to his outstanding service. Whether or not you are a customer buying an engine or just a car guy needing help sorting out a problem, he takes the time to help you get things right.
I agree with Ernie, though, about the originality issue. Aluminum blocks don't have the same really deep growl that you get from the original iron blocks. In addition, I have observed many, many times, how other people seem to "perk up" when you answer their question about what engine is it, and you tell them that it is an "orginal and correct 1966 date code 427 sideoiler engine. the same 427 used in the original Cobras"
I drive mine and take it to shows. Several times my correct 427 has received the overall Best Engine awards, Ford Top Gun award, etc. solely because it is a correct date coded engine for a Shelby Cobra, even though it is in a replica Cobra.
Good luck and enjoy! Bob