Unless you know what you are doing and well versed as a mechanic I would suggest a different truck with a Hemi.
These engines are all computer controlled and would most likely need a new PCM among other things and then have to be flashed and updated to your truck. Not like the old days when you could drop a new engine in every other week and just drive away.
I think I read a thread on another forum where a guy swapped a Hemi for the 5.9 in his 2nd gen. It required a lot of fab work, and I never followed the post to see if it finally worked out for him. Unless you want to do it just to do it like that guy did though I would get a different truck. You will save money just based on the opportunity cost.
Thunderhorse-Built: 25 Feb 2013 Warren, Michigan; Bought: 28 May 2013 Huskyliner Weatherbeaters, door edge guards, Line-X bedliner, Kryptek Typhon Cordura seat covers w/ MOLLE panels (review), Console Vault (install/review), Bilstein 4600s (thread), BFG T/A KO2 LT275/60/20s (thread), Matte black Plasti-dipped center console bezel, BT catch can, Corsa 14405 cat back (video) Tuftruck 1223V progressive rear coils.