David Litfin mentioned to me that Stephen Miller is listed as one of the keyboards players on Harvey Mandel's 1968 album called "Cristo Redentor". He is the same person who played in Elvin Bishop's band and even on a couple Alman Bros albums.
Check it out: http://allmusic.com/cg/amg.dll?p=amg&sql=A56jveae04xa7 Dave S.