Dear Jim,
Just for the record of carb performance, I calculated my fuel mileage over 1711 miles driving to the Reno Rally. The engine is 484 hp 351C with a Holley Strip Dominator intake, CR 10:1 ported 4V quench heads, and a custom Holley 4150 double pumper. The run to Reno included many miles of high speed grand touring driving.
The calculated miles per gallon was 18.7 mph. 17-19 mpg can be done---perhaps not often and more often with custom carbs, but it can be done.
Warmest regards, Chuck Engles