Another vote for Bob Latino. Also, please do not overlook Dynakit Parts, who offer the original ST70. I've twice dealt with Kevin there, and like Bob Latino, he's excellent to work with. The ST70 kit from Triode Electronics seems very good as well, even if I've only dealt with them for non-Dynaco transformers and other unrelated parts
VERY exciting news on the return of the Atma Sphere M60 kit!!!