We found that the capacitors were all in good shape with the proper capacitances. This is in contrast to modern capacitors, which often leak or fail after a few years. NASA used expensive aerospace-grade capacitors and X-rayed each one to test for faults, and this made a large difference.
That's also because these are hermetically sealed wet tantalum caps, not the dry type that's notorious for shorting out and catching fire. "Wet tants" are very expensive and you can still buy them today:
https://www.mouser.com/Vishay/Passive-Components/Capacitors/...
We were somewhat surprised that both power supplies worked flawlessly after 50 years.
I'm not all that surprised, actually --- but perhaps that's because I've seen plenty of videos on YouTube of more mundane equipment, like vehicles and appliances, coming back to life after several decades of storage or exposure to the elements with minimal repairs, so for a clearly high-reliability component like this AGC PSU to work is almost expected.