I wouldn't normally do this but as we seem to be kindred spirits when it comes to Spann, here's a link to an introduction which front's a 120 page Spann career discography compiled in 1997 by Bill Rowe. Sadly Bill never lived to see it published (2000) but it won an ARSC award of merit.
http://ourblues.wordpress.com/2011/12/19/introduction-to-otis-spann-the-discography-compiled-by-bill-rowe/