Fuel Economy..?

The milage on a slat six car can vary widely. Depending on the condition of the engine, the type of car, and the type of driving. In general a slant car in good condition will get about upper teens average. A heavy car in poor condition/tune will get much worse. I have a 64 Valiant with a fresh engine, built for economy, with a 3 speed standard trans, that gets upper 20's mph on the interstate.

PS: a MSD ignition on a near stock slant is a waste of money, if you need to convert from points, a HEI is more cost effective.