That's a great piece, I learned it a long time ago off Davis' Ragtime Guitar LP and still play it. The guy you might want to talk to is Stefan Grossman. I believe he recorded it at the Reverend's home and could probably answer your questions. He frequently posts messages here (the Woodshed). First attempt at blue clicky thing, hope it works.

Regards, Frankie

Link fixed - subsequent attempts deleted.
-Joe Offer-