No start after cleaning up wiring.

Not sure about 1972, but if your ign switch is in the dash and not the steering column (later cars w/ wheel lock), it is easy to replace and cost ~$11 (rockauto). Before that, pull the plug and apply 12 V direct to the yellow wire terminal. If it fires the starter, it isn't the switch. Some people (me) wire a hidden switch in-line w/ the yellow wire so that prison-schooled miscreants can't hot-wire my car. Maybe a prior owner did that. I also like to wire in an alarm that sounds in the house so I can go ask them what they are doing in my car, as they fumble around.