Hi Scott, great color guide for those of us who collect these different color variations. For the 1925-31, I think you might be missing a color (light blue maybe?) based upon Brad's Lefty Grove collection:
Link. Not sure if you will include the 1929 Star Picture Exhibits or the 1931-32 Ruth Portrait Exhibits. Both of these sets have Prize Back and Exhibits back. I've also included the color variations that I know of for the 1920s Boxers/Baseball Players Exhibits.