Whatever you do, avoid the 3.0L SC V6. It's not smooth, doesn't sound good and can't touch the torque the 5.0L makes. 5.0L is a great engine for towing, sounds good and is pretty smooth. I do agree though that swapping an engine in a nearly 15 year old vehicle is sort of crazy. You'll spend more doing it than the car is worth and you can easily find semi-low mileage LR4s from the 2010-2013 period for less than $25K.