Look at
this add, pedal and motor. On the second web search I found adds and pictures for WE motor and pedal sets that seem to have been sold as converter sets for various brands and models, as well as set ups for their own machines.
Some early electrical equipment can be used, but it needs to be looked at by someone knowledgeable, and I think they need to work on how to get the insulation, and if possible double insulation established for the wiring. Luckily GE was one of the better makers from the start, but electrical items made and sold before ca. 1930 wasn't always subject to regulations and official standards.