have a look at my build dude.
I got 215's with the JB lift kit. im more than happy with the results. and im running -13 offset sunnys.
Your thoughts on the driveline were the exact reason i didnt go to the popular 235s or higher. so many people here break driveline bits going up too big, and best of luck to them

. but for me i think its a perfect compromise at 215. I did the cape last year in september and it loved it. didnt have any issues whatsoever (cept for that fuel pressure thing....

)
I was pretty close to getting a TD 80mm kit but then you have to look at castor correction bushes or the uber-expensive snake racing arms. that was pretty much the deciding factor for me to go with JB and im glad i did, saved HEAPS of dosh and got HEAPS more in the kit, rad arms for instance were like 200 vs 1100.
only stability issue ive EVER had was the notorius 80kmh death wobble in the steering, but im attributing that to being a Jimny rather than the tyre/wheel combination. But that solution has been well documented elsewhere on here.
Im yet to try my flex with sway bar removed, mainly cos im a lazy shit, but that changes handling a bit i hear too.
RE: Tcase swap, monley did a kickass pictorial in the other thread, pretty easy to find. I didnt bother doing one cos his was more than enough to help anyone out.
It took me about 3hrs to do, and i wasnt going hard at it. no speccy tools req'd except maybe a rattle gun. dont even need to jack the car up.
Hardest part BY FAR was bending the fricken stupid shifter to suit... i had great fun with that....
If your stock t-case is alright, id just go with that for now. only reason i changed mine is because the chain started slipping like a champ when i dropped the clutch a bit at the lights. Give yours a bit of beans at the next traffic lights to test it. Youll know if its slipping.
If you go with what i did, put some mud guards on before you go up here, my back quarter panels got pretty flogged with stones on the cape developmental road.