Possible electrical issues in my 64 wagon

You can narrow down the problem. With the scenario in post #5, the ign relay would still energise, but nothing from the starter.

When it happens again, see if you can get an assistant to put their finger on the ign relay. If you feel a click, then the relay, wiring to the starter or starter itself is faulty. No click from the relay could still be a faulty relay, wiring, NSS or ign sw.