I am not surprised they were made that far back, but wouldn't have thought that. From my haunts, they really started showing up a lot in the 70's. My 56 EB had them, and yes they were a major improvement on the banjo pegs. They were not easy to find everywhere though. I had a Schaller catalog that listed a whole bunch of cool stuff they made but the distribution was so odd that the store I got it from could only get the tuners and an upright bass pickup at the time. They made a look alike Model G type thing too.
I actually loved the look of banjo pegs, but got sick of the wobbly crappy nature. I did like Imperials though. I think they fit the headstock better.