Do you have headlights, horn, brake lights, interior lights?
Do you have voltage at the coil + [pos]? Should be about nine volts with the key on and 12 volts with the key in the start position.
Check the battery negative cable to ground. Take it off at the battery and where it grounds on the block, clean it up then reinstall.
Check for voltage at the batt. terminal on the alternator.
Check for voltage at the red terminal on the horn relay on 67 and 68.
67 and 68s have power from the battery through the junction block to a soldered buss and on to the horn relay. From the horn relay power goes to the junction box on the firewall and on to power up the whole car.
69s have power go from the spliced buss to the firewall junction.
If you have good voltage at all these points check to see if you have power to the ignition switch and out of the switch to the starter wire and to the coil wire.
Power flows from the switch to the neutral safety switch then to the firewall junction block, terminal L on a 68, and on to the starter. Check if you have power to the firewall junction block from the neutral safety switch with the key on start
Check to see if you have power at the firewall junction block where the coil wire connects.
Then remove the heavy purple wire on the starter and check for voltage with the key in start position.
If you have power to and from the switch but none at the starter I would say you have a problem in the neutral safety switch or firewall junction box.
If you have power to and from the switch but none at the coil pos + terminal I'd say you have a problem, with the firewall junction box.
Or it could be the connector that plugs into the back of the switch.
Or it could be none of the above.