I do NOT believe in modifying historic machinery, and certainly not if it involves mutilating Scott components, but if you must I have seen a video clip somewhere, perhaps on YouTube, of a two-speeder with electric starter in Australia. It was mounted underneath the two-speed gear, and presumably engaged direct with the gear drum, rather than with the engine. However Owen Tyler was riding his two-speeder up to nearly 100 years old, (him not the bike !), and he didn’t need an electric leg….
Brian