electrical issues with the 67 fish

Mister RedFish ? Thats my dad LOL
Dim lighting and dead gauges are the 2 most common problems.
When only 1 of 2 or 3 gauges fails the problem would be that gauge or sender. When all related gauges fail you can just about bet their power supply is the problem ( you can tell by the wire connections that the amp gauge is not related to the other 3 ).
Their power supply is inside the fuel gauge and will need repair one way or another. How is up to you. So...
lets pull the instrument panel again and take it to the workbench. While its out for repairs, use a small nut and screw to attach the 2 amp gauge wires together and tape them.
I added a pic I call the DOH Factor. Please be very careful when handling these instrument panels. They are fragile !
Leave the headlight switch in the car. We'll use you multimeter to find the dim light problem. Please note.. there are only 4 bulbs used for illumination in the entire panel plus they have blue tint diffusers over them. Bright as possible wont be fantastic.

DOH! factor.JPG