Aw, shucks...
Great history, and so rare to find these days (my '63 has been in the family since '65, and *I* don't have that much documented (note to self to start going through some older papers including some of Dad's receipts).
Also, so glad that yours has been so well preserved over the years.
Quick recommendation for the master rebuild: White Post Restorations in White Post, VA. Billy & the crew are absolutely fantastic to work with, and have tremendous expertise with TreadleVac units (assuming you have power brakes; I haven't read that part of your thread here closely). IAC, I can't say enough good about them.
https://whitepost.com/
As for transmission fluid, you'll want to use Dexron III or equivalent, which is fully backward compatible with earlier Dexron formulations. DO NOT USE DEXRON VI as it is NOT backward compatible.
That said, one of the mechanics in my life who taught me much of what I know about cars in general was a transmission rebuilder (he actually rebuilt the Bonneville's trans at 95K miles or so) was of the philosophy that if the fluid is still pink and does not smell burned, leave it alone. He did not believe in changing transmission fluid unless the unit had to be serviced (and thus, drained in the process). Take that FWIW. I don't change my trans or axle fluids.
Dex III should also work fine for your power steering pump.
Again, great story; thanks for sharing, and I'm with Ed: let's see some pics!