1974 Brain Box saves the day.

They are thermal ballast resistors, designed to heat and change value with the heat. As you stated the hot resistors resists more, reducing the voltage to the ignition system to prolong life of it. Then you have the bypass for start condition. That's why the ballast resistor is stood off from the firewall. Got A/C? Run the ignition box on top of the freezing A/C feed. My pipe ices up after the expansion valve in the engine compartment whennits working. The blower resistors for the fan speed control ar in the plenum of semi modern cars to keep them cool. As they are dumping big watts through those resistors to slow a dc motor and that creates lots of heat.