The books THE FILMS OF THE BOWERY BOYS and FROM BROADWAY TO THE BOWERY both list John Lorenz as the singing voice of Huntz Hall in BLUES BUSTERS. Since John Lorenz was a silent movie actor who was long, looooooong gone out of the business by 1950, I bet that's a typo and it should be singer-actor John Laurenz, who did a lot of recording for various labels (and was also the sidekick "Chito Rafferty" in a couple of RKO B-Westerns).