Not sure if in 75 the ammeter is like the earlier models or if it is a remote shunt type. If it is like the earlier ones I would look at the bulkhead connectors. clean, tighten and maybe replace and corroded or burnt terminals and replace any melted plastic.
There is bare wire showing on the fuel pacer wiring. (It is currently disconnected)
Also I was told the voltage regulator was replaced but it looks like the last leaked black goo all over the engine bay.
The bulb in the ignition switch is most likely incandescent and will generate heat. it may have been changes over the years to a brighter( hotter) bulb so that would be something to check