General rebuild parts can be had from any local parts store such as Napa, Car Quest, Weaver, etc....
Never had much for problems with gasket brands, but Felpro is always a good place to start. Napa and JC Whitney carry them.
Tom Langdon carries some of the speed parts you're looking for.
A 390 Holley is a 390 Holley. Won't really matter where you get it from, but you could try Jegs or Summit Racing, they also have parts, etc... for Holley carbs.
