I think you have ’Jaimoe’ aka John Lee Johnson aka Jai Johanny Johanson who was a drummer with the Allman Brothers with ’Jabo’ John Starks who was a drummer with James Brown. But James Brown did spend a lot time in Macon, GA which is where Capricorn Records was and was the recording company for the Allman Brothers. But I wouldn’t be surprised if James Brown tried to steal him from Greg and Duane and ’Jaimoe’ said no because James Brown was known not to pay his band at times..
I never thought of the dead a ’jazz’ type band but that makes sense cause if I’m not mistaken their shows were very improvisational.