The Stovebolt Site Forums The Parking Lot '60-'66 Trucks Best gas mileage in a 60's Chevy?

I have a 64 with a 350 (stock build), 700R4 and 3:08 Posi. Goodrich all terrain tires (all 4 wheels). About 1800 rpm @ 65 miles/hour. Gets 16 mpg on the highway.
Tried swapping out the 4 barrel for a 2 barrel (stock cast intakes), still 16 mpg on the highway.