Driver for mileage

It's do-able. Mine's a 273, 30 over with 10 to 1's and a mild Isky cam. 3 on the tree. 21 MPG highway.

just build it stock, my 67 barracuda convertible (273 2 bbl/auto) got 21-22 mpg with over 100K miles on powertrain.

I`m using the original 273 block at .030 over and approximately 9.5:1 cr. The cam is a stock 2 barrel grind. The carburetor is a 500cfm Eddie, ignition is a MP electronic, fan clutch, dual exhaust, and soon a 2.94 rear gear. I hope to increase the mpg a little over a stock build. Headers help maybe?