MikeofNorthumbria,
You should check out (if you haven't all readdy) African Guitar on Vestapol Videos as well as (if you play guitar) African Fingerstyle Guitar - Taught by John Low on Stefan Grossman's Guitar Workshop.
Bosco also has a CD out on Rounder Records I believe they are his last recordings before he died.
As for Hugh Tracey, I can't find much on him. I've heard he was a great guitarist, but can't find anything he did. He did start The Library of African Music but I can't find anything of his or any other African Guitarist in that style on there.
Anyways, I'd be instrested in hearing that record you mentioned.

Benjamin