Just found the thread on Outers,
If I can make a suggestion, and it might not be an easy conversion, i'd replace the entire steering setup for a later model one.
Those early ones were a #### of an idea with the steering box mounted back in the engine bay, relay rod and bell crank.
The later ones, staring around '68 or so used a Saginaw pattern box (made by Gemmer) at the front of the chassis with the pitman arm connecting directly to the drag link.
Much, much better steering with minimal losses (play)
I used to replace the Gemmer boxes with HQ-WB Holden ones.
They are a direct bolt in, you just use the Jeep pitman arm and are an easy way to get power steering.
The LC g/box and particularly the t/case are miles too weak for what you want. Good choice keeping the Isuzu box.
The old D20 T/case is up to it, but something like a late model Patrol case might be better, just for ease of supply, and as Gwagensteve said on Outers, probably easier to divorce it, you have enough tailshaft length to do it without upsetting angles.
Anyone know/seen the t/case under some of the Isuzu 4WD trucks ?
Maybe that is an easier way to go (can't recall which side it takes the front from though )
<edit> Again, what rear diff is in it ? The L/C t/case takes off the rear offset like a Land Rover, Jeep are centred.
