Phew, tough question of the day.......

I would go with the 400 stroker: The car is already set up for it, you can build it to any power level you want, and the maintenance is simple.

If you are going for something more modern with the 5.7/6.1 then the engine will be out-dated by the time you are done the swap. That is, the 6.4 is already on it's way out, the 5.7 has already gone through significant changes, and I'm sure Mopar is working on the final version of the Hemi; a 426/7.0 liter. To keep up with the new engines is going to be very expensive.

What is it that you want to be able to do with the car?