personally if it was me I would beef up the 4.7L. Put a blower or turbocharge it. Change your gears out to the 3.92 LSD if you haven't allready. You can do a lot more with the money to the 4.7L to make it run than to drop in the 5.9L and the cost of the conversion. I had thought about doing that to mine when my friend totalled his R/T but we sat down and figured it out with the labor and all the parts and everything it was going to run roughly $8k to do it. I'll wait and put a Hemi in it for that.
If you got lucky you might find a 5.9 out of a wrecked Ram or even better yet a wrecked Dakota R/T. Because of the many different engine choices in the Dakota it makes it hard to do an engine swap. Each model is specifically designed for the factory installed engine.
For the cost of the engine swap alone you could end up with a 4.7 producing 350 to 400 HP. Now that would be a lot of fun to drive. I would opt for the 4.7 with the manual trans.
My 4.7L needs lots of work. Engine knocks. Looked online for a replacement motor, but shipping to Hawaii sucks. Looking to rebuild it instead. What sites/vendors would you recommend? Any help is much appreciated. Much Mahalos in advance!