74 Dart 318 Neutral Safety Switch?

I would access the ignition switch connector and start there. Check for voltage on both sides of the switch, and "wiggle" test the connector. Most everything you say doesn't work goes through the ignition switch

I don't believe ANY of that is fused "before" the switch, except for the fuse link, and then you would not have headlights. BUT 74 may be different..............

I THOUGHT I had made a (poor quality) scan of the 74 wiring, but don't see it. You can download an aftermarket wiring diagram from MyMopar, and the 73 shop manual from the same site. THERE ARE differences in the 74--73