Duster Headlights not working even with power?

No , now we are on the same page.
Running power off the back of the ammeter to the headlight and having it light up proves three things; 1) the headlight works, and 2) the ground works, and 3) there is enough electron flow at the ammeter to make it happen. It also proves that all the wiring between the ammeter and the battery is probably ok.
And the problem has to be between the ammeter and the dimmer switch. The red side of the ammeter is the power supply from the battery; The black side is the power going away from the ammeter. So move your jumper to the red terminal and make sure the ammeter is passing juice. All the power for every circuit in the car, has to go thru the ammeter. There is a copper bar in there that is designed to last forever, but the stoopid studs attached to them are easily torn off by aggressive tightening.. so you gotta prove the darn thing is able to pass the juice.
So if that works ,then you are down to just the #1 splice and the headlamp sw.