What mileage does your slant six powered ride get?

I drive mine mostly during the colder months, and it gets 15-17 in mixed driving. It has 3.23 gears, a Holley 1945 from a '75-'80 car (NOS in the box, never even took it apart), 2.25 exhaust, 5* initial, electronic ignition, and a three-speed. I run the distributor that came with the engine, which is a '74 225 out of a Charger (of all things).