Joe,

Sorry to sound so bloody obvious but I just "googled" Gillian Welch and Eric Bibb at random. Both have current web sites with contact details.
Perhaps you could shorten the list this way. Jean Ritchie (Kytrad to mudcat followers)is in ill health but her family posts here from time to time.
Re John Kirkpatrick and Phil Cunningham; Froots magazine in London should be able to give you contact details.

Hoot