Replace the wiring harness completely, everything else would be just stupid. I'm facing the same problem right now. My previous owner had already started patching the cables, but it's a very bad job. All cables too thick, the same color, and only patched with the cheapest clamps in between.
What nobody has said here and many do not know ... The cable itself is extremely aged. The insulation becomes fragile and the copper in the cable is oxidized. (Becomes black / green) This has the consequence that the line resistances increase considerably! I only had 3V of the 6V on the battery on the horn and wiper! This means that they can no longer function properly. It won't be much different with the headlights. Furthermore, such a cable heats itself up and, in the worst case, can even burn itself. It doesn't even have to be a loose screw clamp.
As I said, I also have to / want to completely replace my wiring harness, but I will not take one finished. I will make it myself and upgrade the functions that I still lack. (Fog lights, trafficators, HiFi, heater blower, rear window heater ...) And very important, 13 additional fuses !!!
The cable plan for this has also become somewhat more extensive.

Pic:
http://www.drg-ler.de/Bilder/Ford/Elektrik/aneu1klein.GIF
Greetings from Berlin
Andy