One thing you can do that would make your life easier and might improve your mileage, is to use HEI and PCV valve rather than points and road draft tube.
After that, match the cam, stock compression, 4bbl with small primaries and larger secondaries (or mechanical fuel injection if you don't like EFI), heads, for fuel efficiency rather than performance, add an overdrive tranny, highway gears in the rear diff...
Most importantly, a light foot.
