Gary Burton was also a Berklee local, as were composers of many of the other seemingly obscure selections. Those tunes probably were in fact "standards" in that time and place, and through The Real Book, likely achieved more prominence than they would have otherwise.

I find it curious though that General Mojo didn't make it in to the Hal Leonard "6th Edition". I find it hard to believe that they couldn't secure the rights; did they just deem it too obscure? For trying to recreate the old book, seems like an unfortunate loss. Those tunes gave the book part of its character.