It would seem like a problem at the ignition switch or fuse to me. If a wire has come off the switch or something, this could happen so I would check that out along with the fuse. Or, the switch could be bad. From the wiring diagram in the 68 service manual it appears that the pink wire to the switch should make the circuit when the car is running. With the key in the "run" position, there should be voltage on this pink wire. Some others here likely have experience with this.
