Anyone ever turn an old Dart into an ultimate daily-driver?

Welcome
As for the milage, as long the engine is not smoking, I would say it way out of tune.
16+ mpg should be easy.
Is the choke sticking?
What shape are the plugs and wires?
Timing?
You need to down load a copy of the Factory Service Manual, it is on this site.
Understand how things work, and work on them yourself. These cars are very easy to work on.
If you were close to me I would show you how to do things.
Maybe a member here is close to help out.