one good place to start is the connection through fiddle music, check out Ceolas: the Fiddler's Companion. There are lots of old-time/bluegrass tunes with celtic roots- The Devil's Dream; Froggie; Red-Haired Boy; the "Silver Dagger/Katie Dear" branch of "East Virginia"- the list goes on and on.

Good luck, it will take a lot of work.

Richie