What he has to do is just plain listen to blues tunes, they've all solos in them. If he needs a list of artists i can start him off right here:
Albert Collins
Freddie King
Gary Moore
Howlin Wolf
John Lee Hooker
Johnny Winter
Albert King
Otis Rush
Little Milton
T-bone Walker
Muddy Waters
B.B. King
Jimi Hendrix
Robert Johnson
Sonny Landreth
Eric Clapton
SRV
Bo Diddley
Buddy Guy
Oldies but goodies baby! Gotta go back to the roots if you don't want a watered down version.