In case mileage is still a factor in your thinking, my combo (63 Biscayne, lowered about 5", with 292, Edelbrock 600CFM carb and lump port head, stock 3 spd trans making 65MPH about 2600RPM) is getting an avg 17.3 MPG. That includes sitting/crawling in rush hour traffic. Plus, I'm still dialing in the carb!