Do you have power to the ignition switch and if so do you have power out of the switch start terminal with key turned to start? Have you monkeyed with any of the safety switches like open door, kid asleep on the seat, neutral safety switch at tranny? Is there continuity between the start terminal on the ignition and the start relay?
You no doubt know about multiplex wiring. Just be real careful about probing with a hot wire source because what you think you see in the wiring may not be reflective of what is really happening with the wires.
I'll be interested to hear what you discover.