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

I was having the same problem on my Demon with the Fuel and Temp Gauges and I replaced the voltage limiter with the one from http://www.demonivr.com/index.html and it solved the problem with the gauges. The lights are another problem, could be as simple as a bad light switch, you will have to do some testing when the dash is out.