naaaa, probably the ignition switch is worn out- being that old, I doubt it needs adjustment. Could also be the keyswitch itself if its rounded off and not shoveing the rod down far enough.
down on the lower column is a box with a plug harness- should be above your right foot, and kinda around the top- thats the ignition box. Its got a rod that go`s from there, up to the keyswitch. You turn the key, the rod moves, connections are made, and everythings happy.
Then they wear out- the inside of the box has a slider with contacts for various electric stuff- think keyswitch here- backwards is acc. forwards is start- your rotateing the rod, and slideing the slider down in the box along its contacts. Sometimes the blue wire will fry going into the box. this is caused by 2 simple things. Age, and toys. Too many toys run off the acc circut will melt the blue wire (could be any color-Ive run into blue mor often than not)- no acc, no start, no turn over, no nothing....unless you jiggle it...untill it melts completely.
If this be the case, and youve tested everything else includeing all the relays in the starting circut- head down to the parts store for a $9 or so new ignition box, specify auto or manual-their different, install and go. Might even spring for a new keyswitch-its probably going bad with age.
before you ask- the easiest way to install is to lay the drivers set back, put your head on the floorboard and feet to the headliner, and look up. If your quick, you wont get an anurism or have a stroke.