Taking the plunge

I replaced the heater core first. Then I discovered that the big wire from battery to starter was shorting out on the steering shaft, so I changed that wire, the wire from the starter relay to solenoid, and the battery terminal came with that of course. I also changed starter relay.

So I went to start it and I got no crank and no click. I also had a fuse in the fuse box blow every time the car was turned to run, and the gauges and parking brake/oil pressure lights were dead. Ammeter works fine (on a separate circuit). It had spark and ignition was fine, turn signals lights all worked fine. I could start it by bypassing the starter totally or just by wiring the positive battery to the switched side of the relay (yellow wire).

So I put in a new ignition switch. I've tested it and it works. Now I have the following condition:

With the fuse that used to blow every time I turned the key OUT:

No crank, no click, no gauges.

With that fuse in:

Fuse does not blow
Gauges/lights work
Starter cranks in both RUN and START positions