what combo = decent mileage+ power/torque

he drives normal most of the time 20 miles of intersate a day and tolls around town some ...tows a 22 boat almost every weekend during the summer .....he is trying to justify not buying a new hemi truck to his wife....he likes the truck he's had it for years ......btw he owns a junkyard here in town......so finding a 318 360 400 or 440 is not a problem....