MPG Motor Magnum vs. Hemi

Rebuild the 413 and stick the long ram induction system on it. It was made to give optimum power at highway cruise!
I vote to keep the 413 also. A little RV cam and late model EFI type fuel injection would work well. Mileage depending on what rear gear and tire size, I would estimate mid teens at least on a highway haul. You could always mod a o/d tranny or the like. That 413 could pull any gear combination. Nice wagon!