13-17mpg depending on conditions and my right foot.
Original / stock bottom end 350, Vortec heads (for about 10:1 compression! Chugging premium now!), Edelbrock Performer intake, Edelbrock #1901 Quadrajet, no-name HEI, dual exhaust...the power runs through a decently built 700R4, 3.73 open rear, and 275/60TR15 tires (28" tall).