Those pre-and post war locos I rebuilt, I rebuilt as originally made. Lionel, Marx, and a Jusan. Even rebuilt "good as new," run so much less smoothly at slow speeds compared to today's that I just put them up on a high shelf.
Transferring the body to a completely new, modern, chassis, works wonders, as you would expect. I have done several this way with a tinplate Marx 0-4-0 - I used the chassis from Lionel Thomas line - Percy I think. I used the chassis guts out of the little Atlas Atlantic twice to fit small diecast Marx or Lionel bodies: its small compared to most and so usually slips right inside a traditional 0-4-0 diecast body.
