Intermittent engine not cranking when starting?

My vehicle listed above XE, is not turning over intermittently. The car has a new battery, distributor cap, points etc, spark plug wiring harness, 6 new spark plugs. The car has a sensor that is depressed when pushing the clutch in that enables the message to be sent to the starter to engage and turn the flywheel. The sensor seems operational. The starter has been tested and is functional. The only thing I haven't looked into yet is the ignition assembly. It's a 30-year-old truck/SUV that runs immaculately. When it does start, it runs fine no stalling or roughness. When I turned it off and tried to restart, I got nothing. I hear the clutch sensor makes the proper sound that it's working. I turn the ignition repeatedly, slowly, multiple times, sometimes once or twice. Other times many with no success. If the car sits for a while and attempts to start, it shuts off. If I immediately turned it off, and try to restart, I get nothing. I again try multiple times to turn the ignition key and it may or may not start. It bump starts just fine. My only thought is the ignition assembly is faulty. Any helpful thoughts would be greatly appreciated.
Peter B.