starting problem 65 polara

First, is this an automatic or stick? If it's an automatic, it's much more likely you have a neutral safety switch issue than ignition switch.

Check the relay, auto will have one big stud, a "square" exposed terminal, and two "push on" terminals.

The starter "signal" from the igniiton switch is normally yellow. Using a test lamp, probe the one or two push on connectors for voltage WHEN YOU twist the key to start.

IF you have voltage there, it's not the switch.

IF you don't have an automatic, and you DO have voltage at the "push on" connector, you have a bad starter relay.

If you have an automatic, and you DO have voltage "at the yellow" push on connector, unhook the OTHER one and clip it to ground. MAKE SURE the auto is in park, and it should crank. This bypasses the nss.

IF YOU DO NOT have voltage at the yellow "push on" connector, IT MAY be the bulkhead connector instead of the switch.

At this time, probably easiest to go ahead and pull the switch, use your test lamp to probe the yellow coming off the back of the switch. Once again, twist to "start" the yellow should be hot.

It would pay, I believe, to pull the bulkhead connector off and clean it, as well as the connectors on the headlight switch and ignition switch.