[Bored&Stroked]

My recommendation is to read the wiring diagram very carefully and then take a volt-meter (or even just a current tester "light") and start tracing from the battery, through all the connections/circuits until you find your problem. Be very methodical about it - starting at the beginning (the battery) and working through the system - all the way to the coil. You'll find a place where the voltage either drops substantially, or isn't there at all. If the wiring is stock and the fuse(s) are in place, then the most likely cause is corrosion or a bad connection in general. Take your time . . . you'll figure it out.

From what I can tell on the wiring diagram, there is a main wire to the ignition switch that comes off the junction where the heavy gauge power lead comes from the battery to the area where the ignition resister and what I believe are circuit breakers(?) exist. I'd start at that location, then head to the ignition switch, then to both sides of the resister . . . you'll find the issue.