A bunch of suspects here. I sounds like you have a problem in the ignition switch circuit.
Make sure the battery grounds are good a the chassis end, and to the body.
Check the start wire to the relay with a test light or meter. If you get 12 v, then suspect the relay.
If you don't get power there, I would look at the ignition switch adjustment on the column, and the neutral safety switch, and, or clutch switches. Beyond that, it may be a wiring problem.