Looks good Brad. When bending seamed tubing,I always try to put the seam to the inside of my bend radius. I have no real world experience with this just have heard it is better if you don't stretch the weld.
I hated my shackle reverse when I had leaves. It would hoop on climbs, the pinion would move to much and you need a long travel driveline.
Add that to soft YJ's and you'll be flattening and "S" ing springs left and right.
I don't know about the truck axles, but lockrights have held up fine for several years in my landcruiser axles under my samurai with 5.29's, longs, and sticky tires.
I'm not saying that there the best but they've work great for me.
I was running a mod toyota pump but now a KRC high output (TC style).
37" tires. I dont know the lock to lock right off hand but its pretty quick maybe 2.5??
lincolnlock helped me choose mine.
https://www.surpluscenter.com/item.asp?UID=2009063000201730&item=9-1882&catname=hydraulic
I have a 2x8 single ended psc ram. I really like the fast steering.
I guess I did kind of give you some bad info. It is doable but not as easy as throwing it under you truck(if thats what it's going in).
Unless you have a spare set of mini knuckles on out and some mini shafts laying around, I'd use a truck axle also.
I think if you got some after market gears...
You can put truck knuckles and shafts on FJ axles.
Thats what I have on my samurai.
1972 fj40 axles
toy truck knuckles and brakes
trailgear flanges
30 spline longs