The 3G Hemi is a great engine. I'm on my third (DD). It likes to spin and is easily upgraded for more power with great flowing heads. It likes at least 4 gears... more is better. It will loaf along at low RPM in OD and get good mileage but again, it likes to spin to get up and go. The 440 is a great engine also. With tight quench, good CR, OD and a well tuned carb or EFI it can be reasonably efficient. Its strong point is mid range torque... different animal.

Is it worth it? Up to you. I believe the 3G swap is getting easier but not yet "easy" and that's a consideration.