Okay, I am cutrrently doing a ZF auto conversion on my 83 Rangie and I have found out (the hard way) certain things need looking at.
Firstly, especially going from manual to auto check that you have some sort of wiring diagram so you can work out where to plug your park/neutal switch into to stop you starting the Rangie in R or D,3,2,1. Back in '83 LR still made manual-only models, but yours being a later model it wouldn't surprise me if the plug is there, so thatwould be a simple hurdle. Mine's off to the local auto sparky, not good with electrical me so that can be left to the experts
Also I had to fabricate the kickdown cable mount. Yours may need doing so too, but may already have provisions for it (if you still are running the standard 3.5 EFI V8) but once again I had did some home fabricating on the throttle spindle to get ti to fit properly as well as make up a l-shaped bracket to fix the cable to the rocker cover. Not hard, but fiddly. It's important that you set the kickdown cable up propwrly or you could risk damaging the ZF. If you are not sure, have it set-up professionally. A small price to pay compared to rebuil;duibng the Zf for a larg cost (it's is here in Australia).
The output ahaft will only need replacing if you are fitting up a LT230 from a later Discovery (95 onwards I think). I had to fit a new one because I had the same issue. Not to worry, better off doing it nowthen skimp and finsd out a few months down the trak that it will need re-newing 9common sense really). If you can, pick up a later 'T' series LT230 because it has the cross drilled output gear and won't wear the shaft out unlike the earlier ones without the gear drilled out.
There are other obstacles that will need doing, but being that yours is a later model it will be a bit easier than doing one on an older Rangie like mine. The fiddly stuff and sometimes 'snags' along the way are definatly well worth it long term. ZF autos are much better 'box than LT77 would ever be all-round.
I'm sure I have left a few things out, but there's plenty of knowlegeable blokes on here that may fill in the holes.
Good luck with the conversion. Like I said, you won't regret it.
Trav