For a daily driver with gas mileage in mind:
Stick with the 1bbl. I like the Holley 1920
Stock cam.
2.93 gear.
Stock exh manifold.
2.25 exhaust,free flowing muffler.
Chrysler elec ignition.
Fresh Autolites,wires,cap & rotor.
Tune it up, and see if it likes a couple degrees of advance.
Between the new tune, and the new exhaust the car will run much better, with a seat of the pants gain. When I was playing with this same set-up, I went up 2 jet sizes, with the opened up exhaust.
But then again, I run Cliffords, so what do I know ?