The 6.0 transmission will not directly swap (which is a real shame as the 5r110w used in the 6.0 is superior, and is the same for both 2 and 4wd applications!)-at the very least you would need a PCS stand-alone controller and tuning for the trans. As for the 4x4 conversion, it is very simple (minus the transmission, which you either need to replace the output shaft/case, or use a 4x4 trans). The frames are identical, all the holes are already there-the 4 rivets that hold each spring bucket in double as the 4x4 upper shock mounts. You need the complete front differential (make sure to get one with a gear ratio that matches your rear), leaf springs, fore and aft leaf spring hangers, pitman arm, track bar backet, transfer case (they have a different input shaft spline pattern for auto vs manual transmission), and driveshafts. If you decide to get a manual transfer case (np271), the swap is VERY simple. The np273 is much, much more complex if you want the ESOF to function properly. I prefer manaul transfer cases anyway.
The 05-up suspension is a better choice. You re-use your coil spring buckets-and the turning radius is superior by far!