IMHO skip the solid axle conversion if don't plan on wheeling. The IFS is much better for the highwy and would be a less complicated swap.

The easiest thing to do would be to buy a wrecked doner vehicle and pluck the parts off of that. You will be forever fetching parts or wondering how things fit/parts needed if you don't. That said, unless you really want the challenge I think you would be better off selling your rig and buying a 4x4.

As far as helping resale value, if you were 4x4 shopping would you rather buy a factory 4x4 or one someone had converted? It might actually hurt the resale value of your rig if it is perceived as being "butchered". Conversions done by professional shops often don't increase the value of the rig.