Ridjobradi, I ran 1/8 nylon tubing for a while, and found no difference in the function of the ARB's compared to the larger 5mm.  The smaller nylon has a better tolerance to heat, and fittings are almost the same.  The through the wall differentia fitting was a concern to me so I went back to the 5mm tubing.
I made all arms.  (I have made almost everything on my Tracker.) My lower arms were 29" and I made robust outside frame mounts with 4 holes for adjustments.  (I could not detect differences in using the various holes, but the 4 link calculator shows differences.)  I recently made a new crossmember to attach my lower links more towards the center and am currently running that.  (During recent motor swap I discovered that my ds back control arm bushing was shot, which probably was the cause of wandering that was the reason for changing lower link points.)  I do like the 4 link suspension,

Not sure if you check this thread still. but any advice on how you tied the HVAC into the new XL7 harness?

I grabbed a hot wire and used it for the original heater controls, and I have removed the AC, not room for heat exchanger.  I do have an electrical drain that is hard to find.  I found two relays that were stuck closed in XL7 relay box.

Tried to PM this but the Capatcha thing doesnt work.

I really appreciate your advice. I am getting really close to starting my swap- I have my harness out of the XL7 (Entire harness), engine and trans are out, and about every component from the XL7 in my garage waiting haha...

The HVAC is my main concern. Did you leave a piece of the original harness for this? You said you grabbed a hot wire, so I am guessing that is the way you did it.

Another question is the speedo-did you use the XL7 speedo? If so how did you mount it (Looks like its going to need some custom work!)