Looking good so far!
Not to toot my own horn, but try to copy my build as close as possible, it worked amazing. If the guy that setup my gears hadn't screwed it up so bad, and if I was throwing a big heavy diesel up front, I'd still be running it happily. The only thing I would NOT do is mount the shock towers like I did. I fed nuts inside the frame and welded them in, then bolted the F250 towers up. Ended up cracking the frame. If you want to try a similar approach make sure you drill through to the other side and put a sleeve in.
Don't buy any DIY steering kits unless you intend to move the tracbar mount. The funky Jeep brackets will interfere. Just use stock V8 ZJ steering, it's fairly beefy. The drag link will be a little too long, I cut about 3/4" off the threads, then use a pitman arm TRE from a 84 J10, it's the right length and threads.
The XJ springs are a little on the soft side, yes. But I ran them for quite a while and they worked pretty good and didn't sag too much over time. I believe my springs were 6" Rough Country, I gave them to my XJ buddy that had Rubicon Express 3.5" coils and he loves them, much softer and better ride for his rig. The RE coils are rated ~240 lbs, the RC ~180.
I see you ended up with the adjustable coil buckets from Ballistic. Good choice, but I had to modify mine, my coils sat like this \ / and the buckets rubbed my tires.
I've got my whole front end torn up right now for the engine swap, let me know if you need any specific pictures and I'll get some.