Nice car, man. I'm a fan of the old styling on cars, they just looked "cooler" back then, in my opinion. Does your car have a catalytic converter? you could be damaging it with the adjustments to the carb, try and find a mechanic that has an exhaust gas analyzer, that way you can balance the emissions.
If you want to increase your economy, you may want to try to locate an electric fan for the radiator, they are much more efficient than their belt-driven kin. Also, you may wish to increase the size of the air filter, she looks a bit too small, I may be wrong.
Also, when you are driving the Pizza delivery truck, try some engine off coasting if you can, that will bring you up to the EPA amount, even with the starts and stops.
Good luck and welcome to ecomodder!
p.s. Check out this thread, it has a very similar car to yours