Just wanted to update this. I have all four shocks on now. I had to modify the rears by having 90 degree fittings and custom lines installed. The driver's side reservoir can mount to the shock body, but to avoid the heat from the exhaust I mounted the reservoir to the chassis on the passenger side. As mentioned, bushings need to be swapped.
The fronts are NBS 2wd and basically bolt right in. Even though the bottom eyelet T bar mount looks identical, I had to ever so slightly enlarge the holes with a drill. The shock BARELY fits into the lower arm, so its probably as big as you can go with the stock lower control arm. I figured the NBS and OBS are close in weight and weight distribution, so the valving would be fine. The shock dimensions, stroke are all peachy (I have a Fabtech knuckle lift)
Bilstein 5100 Vs. Fox 2.0
What most people's impressions online mimic what I felt. The Bilstein's are awesome shocks, but the valving is more catered toward a confidence inspiring street setup. They are relatively firm on lighter bumps but make the vehicle handle well. I went on 2 trails with this setup and it was quite bumpy. The Fox's however, with their linear valving, were more compliant (not necessarily softer), and more comfortable over rugged terrain. I took these on a test attending King of the Hammers
(as a spectator of course!)