Back in the days when my '49 Coupe was basic transportation, I used to regularly jump start it from 12 volt systems without doing either my starter, or the amperage donor any harm. I don't plan on a 12 volt conversion, but if I did, I wouldn't hesitate to trust the existing starter.
Funny thing, now that I don't depend on the car, I have the means to maintain it well enough that I don't need to jump start it.
