Fuel mileage. Stroker vs. stock stroke

Gearing, powerband, combustion efficiency, weight, and to an extent aerodynamics are the factors that are going to affect mileage. Get a good closed-chamber head (with well-smoothed edges in the combustion chamber), as high compression as is possible on pump gas, a mild cam (for the displacement you're looking at... that makes a difference), single-plane intake (dual plane will just slow you down in the top end unless it's REALLY big), and finally a Thermo-Quad would give you the best mileage (although an Eddy Thunder/Performer 4-bbl would probably be more appropriate for your application). Then go with a rear-end ratio or overdrive tranny that would spin your engine at a speed within the torque curve (preferably near peak torque).