Dome light...

When you say you've been messing with it what exactly do you mean, the headlight switch or the door jam switch?

Do you have a factory wiring diagram? That would help a lot to identify the wires. It does sound like a door switch and that's where I would look first.

The door switch interrupts the ground. If you remove the kick panel you can usually get to the wiring that feeds into the switch. It could be either front door switches if that's where the problem lies. If you unplug them, you can check their continuity to the ground with a meter. When pushed in they should open the circuit and you should lose continuity.

If the door switches seem to be working properly you can try a headlight switch from a boneyard. I don't know how well the supply is out there but all the yards that have older cars out here usually have several mid-70 a-bodies available.

The headlight switch has a coil of wire that works as a rheostat to dim and brighten the dash lights when you spin the knob. When you turn it past the brightest setting you will feel it click as it makes contact and the dome light will come on if it's working correctly.

This is likely a little different than yours but you can get an idea. http://www.ebay.com/itm/Nos-Mopar-1...Truck_Parts_Accessories&vxp=mtr#ht_500wt_1081