Bullfrog, Try Woody Mann's "Six Early Blues Guitarists" for Blind Willie McTell (three songs) and some other great ones. (Note: early editions were titled "Six Black Blues Guitarists").

For Blind Lemon Jefferson, I've seen some transcriptions in a book by Stefan Grossman publised by Oak Publications. I can't think of the right title, but it's the one on Ragtime Blues. It also has some McTell tunes.

I think I bought both these books at a local music store which specializes in accoustic instruments. I would guess they are still in print and available. If you need more details on either, send me a personal message.