1984 f150 not starting

Make sure battery has a full charge and connections all good, on both ends, not just at the battery. Check for voltage at your fuse box, use a test light. Some fuses are hot all the time, some go hot with key on, check them both ways, for voltage. Might be problem with ignition switch, I can't tell from here? You could check voltage feed to and from ignition switch? Could be an issue with fusible link, follow B+ cable. My wiring diagrams for this model aren't very good.