Ok! Thanks to
@Mercian and Stuart Bray we have a functioning bike again! Here's what's new:
Bought a set of NOS brakes for $6 USD + $22 USD Shipping from the UK, lol. Just as
@Mercian said they fit the brake holders and weren't hardened. I'm not a bike guru so probably the install technique leaves something to be desired, but it DID work:
The inserts were a bit too thick for the rims so I sanded them down to fit:
Then put em on. They "only" took about 3 hours to install (novice, lol).... plus about a month total to see if Mercian's worked, then buy them and have them shipped.
I also put on the repro grips from Stuart Bray. Holy cow they were expensive, but necessary. I installed with a 1/2" band of brown card paper just under the leading edge of the grip per his instructions to replicate the original card that peeked out and held the glue. You can barely see it but it's there. I filed down some rust first, and the whole process for that took about 1 hour.... plus a month to find, buy & receive them.
Yesterday I rode it for the first time since I was a kid. The brake pads still rub some so there's some fine-tuning to do... either that or just ride it enough to wear them down. I'm afraid of putting too much pressure on and breaking the chain, too, so rode it pretty gingerly. Plus I still need an appropriate saddle, which will probably be either a Wrights W3N or W3ST.
Thanks again to those who supported along the way. Your effort helped get this bike rolling again!