If you already have a spare xfer, wouldn't a crawler be an option worth considering for just a little more $$$? It wasn't for me with a 97" WB and my engine placement [the rear driveshaft would be really short], but it would seem to have more flexibility for you; that way you could have both 2.28 and 5.20 ratios available.
I installed the gears myself, just like everything else on my rig. For an average mechanic, I would say it is not that big a deal. You might as well also put twin sticks in while you have the case apart; they are a godsend with a front auto locker.
My shift patterns are substantially different than yours would be since I am running a 3-speed automatic [see John Anderson under Member's Rigs for complete vehicle specs]. Lo-3rd is 19.27 CR with my 4.10's, and that is too slow when trying to travel any significant distance, so I must shift to hi. Your OD might be OK in low, depending on your diff ratios.
I have been shifting my early Toyo gear xfer from low to high and vice versa while rolling [at reasonable speeds] for 20 years without much problem. When I used to have a 5-speed manual, I would just dump the clutch, shift two tranny gears [up or down as appropriate] and let her fly. With the auto, I shift to tranny neutral, quickly hit the xfer, and then grab the appropriate tranny gear. It is a little harder to avoid grinding with an auto, and definitely harder with the 4.7's, but manageable. The gear xfer seems to be a little more tolerant than the chain case in my old Taco was, but even that wasn't bad with a 5-speed; maybe I just had alot more practice with the gear case.
The brake upgrade was the standard IFS V-6 [4 big pistons] calipers and FJ rotors. It made a big improvement, particularly with my relatively large rear disks; definitely worth the price of admission, and completely bolt-on [except the calipers may need to be clearanced depending on you wheels]. I would highly recommend this mod.
Let me know if you care to discuss the details of any of this further; I have been running Toyo 8" axles and gear xfer in various configurations of my rig for 20 years.