So I picked up a 1970 Duster today, got some newb questions

See if the dimmer function on the headlight switch is all the way off. Could be the headlight switch itself. Not uncommon for the pin in the back of the instrument cluster to be broken or oxidized. Light bulb burned out. Check the connection on the sender for the fuel. It needs a good ground. Check that you have good solid grounding from the block to the firewall etc...

John D. Beckerley
Austin, Texas