[WFBowen]

These generators are fully rebuldable - if you haven't, contact a shop that specializes in generators/alternators and give them a try - it's the easiest solution.

Another solution would be to purchase an alternator kit for the car - straightforward installation and you'll have a modern charging system.
Next would be to find all the bits and pieces for the later, larger generator - it'd be easiest to find someone scrapping a later motor and just buy the entire assembly from front pulley to cooling fan including the mounting stand.
Good luck,
Bill