I did some research and here's what I found out so far: Sonora declared bankruptcy in early 1957 and stopped production by a least then, if not earlier. In 1959 Trav'ler bought the name and announced they were going to begin selling products with the Sonora brand again. In other words, Sonoras were just re-branded Trav'lers after that point. I looked at some of the Trav'ler portables from 1959-60 and they sure are the same style as Bob's set.

I have a Sams index from 1962 and I cross refrenced the Trav'lers and Sonoras together. I was able to eliminate some of them, but this is a list of the Sams folders that I can't find any info on to know which models they cover and/or a picture to know if it's Bob's set: 413-2, 472-15, 497-2, 502-2, 541-2

Maybe somebody has these folders and can look to see if they match Bob's set.