Does my /6 sound right?

You've taken the chassis out of the bad fuel mileage equation. All seems to be OK there, for now.

Suggest:

1. Get the spark timing adjusted properly, check the coil, wires, and plugs.
2. Check distributor vacuum hose to carb connection. Check for a vacuum leak, e.g. hoses, carb-to-manifold seal, intake-to-cylinder head seal. Check intake manifold for cracks.
3. With the above accomplished, run the engine a bit to check carburetion. Pull a plug to "read" it. There are on-line sites that will give examples for reading plugs. Beats anything I could describe with words.

If the original carburetor has been replaced by a re-man, if my experience is any guide, it is jetted WAY too rich. My Holley reman for the '73 came with a 65 jet when it should have been a 51 according to my manuals. (Summit had the jet[sold in pairs]. Rock Auto had the rebuild kit needed to replace the carb gaskets.)

My manuals are archives. They do not account for the 10% ethanol in the fuel supply.