Agree there.
@Penstarpurist , what kind of mileage are you guys building for? What numbers would be good for you? If you're thinking low 20's you are really close with the combo you already have. Mid to high 20's might be a tall order without a O/D and then if you throw much performance in the mix, your mileage will go away. You can build a more efficient 318 with better than 2 barrel performance but there is a line of diminishing returns when more performance starts killing mileage. Small camshafts are good for mileage. Thermoquad carbs are good for mileage. Small tube headers and smaller dual exhaust are efficient. Heck even stock manifolds with a nice 2 1/4" duals will increase mileage. A properly tuned distributor and more initial timing can increase mileage and performance. I think aluminum heads are a waste for your goals. Bottom line is, up to a point in performance, you can have it both ways. Too much performance, mileage goes away. This will be a interesting discussion.