No Headlights or dash lights
Fix what is there before you go LED
Some general comments some of which has been covered
the light switch has TWO separate battery sources........one is unfused to the switch from the ammeter circuit and operates ONLY the headlights. The light switch has a built in breaker
The second source comes from the tail lamp circuit and provides power for the tail/ park, and instrument lights. The instrument lamps (dimmer controlled) have a small fuse in the panel AFTER the dimmer control
As mentioned, check or fix the cluster connector pins. Find a solid state gauge instrument regulator/ limiter. Tighten/ loosen the gauge stud nuts to clean them and tighten. Check and solder a jumper across the contacts to the IVR socket if necessary, they lose contact. Run a separate ground pigtail from the cluster common point to the upper column support
Check headlight ground which is a ground lug out on the rad support, usually. Both sets of headlamps ground to that one spot---at least on earlier cars
Look up threads on here about bulkhead connector problems. THEY ARE a problem
Do a search on here. There are scads of threads on lighting, cluster, and bulkhead connector problems. After all this wiring--and it's connectors and switches--is getting quite old