For supplies, I recomend Brownell's. Their selection of parts and gunsmithing tools/supplies is about the most extensive I've seen. And their service is fast. In addition, there are many sources of good gunstock wood, both pre-carved and blanks.... (I assume you are going to use wood, and not plastic, for the handle.........)

I have had excellent results using Douglas Premium Grade barrels, but many others are as good-Shilen, Hart, Krieger, etc.