Eddie Lang's guitar solos were published, as I recall, by the Robbins Music Corporation of New York. I used to buy them from specialised shops in London as a teenager in the 1950s. But they were all thrown out when my parents moved home and were trashing, as they saw it, useless bits of paper lying around the house. I was working away from home at the time in one of my first jobs. Is it any wonder that generation was 'mixed up' and those who could afford the haircut were trying to look like James Dean? Sadly, I cannot help your further in your quest for transcriptions. But maybe some our our American friends can point to a present day publishing source of these golden pieces of the plectrum era. While they are at it, somebody else might know were to find a copy of the lovely guitar solo, In Languid Mood, by Louis Gallo in tribute to Eddie Lang.