Re: 67 courtesy light help.
In later years they could be had apart of the aux. lighting group option as an extra cost.
Regardless of "correctness", as stated, orange wires in the courtesy circuit are hot at all times (protected by the 20 amp courtesy/clock/lighter fuse). The bulbs have this + 12 volt connection, they are off until someone opens a door or rotates the headlamp switch in which the white wires provide the switched ground connection.
As far as the heater...to be honest I'm surprised you don't have bigger problems....that fuse box clip rust looks terrible. That is a major issue as far as voltage drops and reliability and even safety issues. You could try to clean the rust, but usually the connections behind the clips inside the block are also corroded. Maybe the time to think about harness replacement.
-If you don't stand for something, you'll fall for anything.