It all depends on what is your definition of rebuild.
If you are looking at a referesh, get Dr Evil's video.
If you plan on fully rebuilding the gearboxes, watch these very detailed and well made videos on YouTube: Klassik Automotive Training School on YouTube
https://www.youtube.com/watch?v=z-QKVY9o4NUhttps://www.youtube.com/watch?v=fE_esA2Piw4https://www.youtube.com/watch?v=z-QKVY9o4NUhttps://www.youtube.com/watch?v=fu3iBJKfvzshttps://www.youtube.com/watch?v=keNZ7j_bxI0Tools; combination of make and buy. Dr. Evil shows a few example for a refresh. If you are doing the full rebuild, harder to find and more expensive tools are required (pinion depth, backlash and preload).
With these gearboxes being 50 years old, chances are someone has been in there. Can you trust the existing gasket thickness which sets the pinion depth and impacts the backlash as being the correct one? Not sure I would...
Good luck with your project.

I refershed two gearboxes in the past using Dr.Evil's video. A lot more fun than derusting a 914. Next gearbox, I plan on going the full deal based on the Klassik series.