No idea about what still exists, but this Don Redman material has
been issued on at least two CDs (from dubs, I presume). These are
"Complementary Tracks" by Classics and "Hot Lips Page Story" by Jazz Archives.
Full details of the Emperors of Jazz recordings may be found in
Ruppli's Mercury book and under Phil Napoleon's name in other jazz
discographies (and a quick Google search of "dixieland classics"
"phil napoleon" will also work). The sessions were April 10, 12, May
16, 17, 1946 in New York. These made it to LP on EmArcy but
apparently not CD (though I see some homemade transfers being offered).
mike at jazzdiscography.com