Hmmm.....permanent. I'd personally not run bigger than a 35-36" tire on any XJ without significant body/structural bracing/mods, so I'll answer from that perspective assuming you're keeping a D30, front and whatever you have in the rear.
Drop brackets are nice, Wayne{UtahXJ} runs them and bangs them sometimes. A nice long arm conversion is pretty cool, but I'd do that with just some heim or Johnny joint ends you can get from Rocklogic or Suka or someone--(get the absolute highest quality you can) and plan on running a limiting strap so on steep stuff you don't dump your junk.
I'm working on changing my lower control arm mounts on the front axle to change the LCA angle and keeping the short arm configuration. This does three intended things--1) cleans up the bottom of the axle so I can get rid of the bent to he!! ones, 2) gives me better angle for nicer ride on road {similar angle to like a 2" lift} and will decrease the need for my axle as it droops to have to drop further to climb weird ledges (it'll still do that but only on very extreme climbs--not nearly as often as it does now), and 3) keep the body/frame mounting point the same as it was engineered from the factory and keep the banging down from a drop bracket. There are some side affects that are possible, but I think I'm going to do it and see what happens and work out the bugs from there.
There are TONS of threads on this on the NAXJA board if you'd like some more reading----(Long arm vs. short, Long arm vs. mid arm, short vs. long, mid vs. mid, short vs. short, long vs. long, etc.)