318 automatic, 3 speed, slant six, your perfect choice for a daily driver

Both my Darts need work now, so I've been driving my '69 Charger R/T daily for months now. I can't see having to drive a small block every day again. Good thing the '69 Dart's getting a 500" motor. I think I'll have to give the '64 to my daughter. So what are your goals? Do you like some power under the hood, or is using as little gas as possible the goal? How about telling us what MPG you want, and then see what combos people have that meet that goal.