It sounds like you want all that, but you don't wanna spend the money or risk the reliability. Yes a built motor will be just as reliable, however you need a trans, a converter, timing chain, oil pump, rods, springs, retainers etc to make any of that worth while. Once its all in, and you start beating on it, thats when stuff will fail. Daily driving and occasional beatings will be fine, but don't think you can put 100k on a built 6.0 pounding it all the time.
For your situation, I would Install 6.0 with nice headers, intake and a tune. Then start collecting parts from there if need be.