More on rewiring:

After many delays, I finally pulled all of the stock wiring out of the car. Pulling long runs through small holes with old grommets is hard work. I cut up some sections to make it managable. I was originally hoping to reuse some of the wire, but have since abandoned that idea. Old wire tends to have brittle insulation, and I've now seen cars with insulation so bad that just bending it slightly would break the insulation.

I'm using SXL wire, which is plain stranded copper wire with a modern heat-resistant insulation that should probably outlive me. You can get this wire from a number of places online. Waytek Wire only sells it in 250ft spools (minimum), which adds up to way more wire than you need. You can also only get 12 solid colors. I've had to be fairly inventive on how to use 12 colors to do the whole car without duplicating colors too much.

Everywhere, red is unswitched +12, black is switched +12, and brown is ground. The other colors are:

Front trunk:
Low beams yellow
High beams white
Fogs purple
Left turn gray
Right turn tan
Wipers orange
Horn pink
Fuel level green(4)
Fuel level light green(5)

Green is generally "sensors", and I'm marking the wires with numbered tags to separate them. Note also that I'm restricting myself to one-speed wipers. One could just number tag two orange wires to get two-speed wipers. I'm not showing any headlight motor wiring, partially because I'm intending to not use them (GT-style manual raisers), but wiring them up would happen entirely within the trunk itself. One could use blue for the motor switch to the relay, which (I think) is the only other wire required.

Engine bay:
Coil+ black
Fuel Pump black
Starter yellow(2)
G light blue
Tach green(1)
Oil Pressure green(2)
Oil Temp green(3)

The starter wire is numbered as the factory uses yellow for both low beams and the starter, and I'm going to use yellow for taillights as well as headlights, so the numbers are to separate the starter and taillight wires, both of which have to pass down the tunnel through the firewall to emerge in the engine bay.

Rear trunk:
Taillights yellow(1)
Brake lights pink
Left turn gray
Right turn tan

No reversing lamps. The brakes and the horn both use pink, but they're never really near each other in the harness, so I'm not bothering to number them.

Note that his omits any fuel injection wiring, which, if you're using D-Jet you should just handle with Jeff Bowlsby's repro harness. If you're using aftermarket stuff, like MS, watch this space, as I'll be going that direction.

My plan now is to have a front trunk harness, a dash harness, a tunnel harness, an engine bay harness, and a rear trunk harness. I want to use connectors that allow me to break the harness into these sections (Weatherpak) so the harnesses can be completely removed without lots of pulling long sections through small holes. I'll enlarge holes as required for the connectors to pass through. One day, I'm going to strip and paint this tub, and I don't want to redo this wiring then.

In the front trunk will be a relay board to hold the four relays (hi, lo, fog, horn) and fuses. The long run from the battery to this front board means two 10 gauge red wires will be required. I'm estimating about 30amps total load here with fogs and high beams with the wipers going and the horn blowing. Over the roughly 10ft run, one 10g wire is marginal here. One 12g is marginal for half of this load, so two 10g it is. These two wires will actually run from the battery down the tunnel across forward of the pedals and to the stock junction block in the driver's footwell. Then, from there up through the scuttle into the trunk to the relay board.

The dash harness will connect the gauges, switches, and dash lights into one harness, or perhaps two harnesses (gauges and switches).

The tunnel harness will simply connect the front trunk/dash with the engine bay.

Since I'm considering Megasquirt for the future, I'm planning on using a waterproof box where the stock ECU goes to hold a relay board and the ECU. For now, just the relay board would live there. Pelican Cases (no affiliation with Pelican Parts) makes two likely models, the 1400 and the 1470, which should fit in the ECU space and should hold both neatly. The will be bulkhead connectors to separate things going in and out of the box to keep it all waterproof. The stock relay board will simply vanish, and I may even remove the mounting bits.

The rear relay board will initially just consist of two relays, Main and Fuel Pump, and the Fuel Pump relay will be switched by the Main relay, which will be switched by the ignition key.