You mentioned the rear marker lights didn't work is that correct? If so you may have a grounding issue - its a notorious problem in these cars. Are the two rear grounds attached in the trunk? They connect to either side of the trunk latch from the rear tail light harness. And while you're at it I'd check the grounds in the engine bay for the marker lights. They should connect up to your radiator core. The problem I ran into with mine was that I had the radiator core powder coated so I wasn't getting a good ground from the surrounding sheetmetal so what I had to do was run a dedicated ground from the battery to the radiator core.
After that, I'd make sure the bulbs are good. Next obvious and cheap fix
Up next I'd replace the headlight switch.
After that it would be time to start tracing the wiring under your dash and through both the forward and rear light harnesses to see if something got cut, burned, etc.