A worked 318 may be better on gas, but it still isn't going to be a peach.
IF you have a big block and your looking for a fun street car, that is the way I'd go even over a stroker S/B. for the very reason Terry stated. The 400 can go to a 451 easy or even a 500 without batting an eye.
Torque! And plenty of it will make the car.
