Lighting gauges: proper spot to splice into dash light power?

Also- the orange wires are dash light circuit, radio light is a easy place to pick it up. Your cigarette lighter wire is hot all the time- is that what you want? If so-go for it!
This is a good point. The cigarette lighter is always hot on these cars meaning your volt meter will always be on, and be a draw on the battery. You probably want it switched.