Great vehicles, but then I'm biased. Ive had one for the last 10 years depite not even liking them when I bought it. Remarkably capable in stock form. Drove mine pretty much stock except 33"s and a 2 inch lift for about 6 years and it did everyting I wanted with plenty of room for the family (mine is 5 door wagon).
Wouldnt use it as a daily driver though. Mine has 5 speed Santana box and fuel is fine for a second vehicle/toy but would not use it for a work/commuter vehicle.
About 4 years ago I pulled it all apart and got rid of all the rust, put new brakelines in and fixed oil leaks. Blasted and POR15'd the chassis. Didnt rebuild the motor or panelbeat it though. Still looks the same battered landy on the outside.
As said above, rust in the firewall is common. Around the footwells and by top front door hinges. Also steel door frames rust behind the alu skins. Rear crossmembers are also prone.
Mine is 1989 and has SU carbs not strombergs as on the one you are looking at. SU's would be my preferance. No diaphrams to perish and good on angles. Easy to set up once you understand them (despite some people telling me they were the devils work!). Late 80s also saw electronic ignition as standard along with SU carbs, also a bonus. Engines will stand far more advance than the 6deg that the manual says. Gives quite a boost in performance for nothing.
Drive train "clunks" are common. Biggest culprits are A frame balljoint on top of rear axle and/or splines between gearbox and transfer box getting flogged out. Center diff can also have freeplay. Add all these together and you can have quite a lot of play and clonking when you go from 1st to reverse.
A frame joint is easy and inexpensive to fix. Center diff is very cheap to re-shim with genuine shims but fiddly and time consuming. It would be expensive to have it done by a mechanic. Spline wear effects the inner splines of the transfer case input gear which is fairly cheap and easy to replace without even removing the box. It comes out through the PTO inspection cover. The later input gears are "cross drilled" with an oil way to prevent the problem re-occuring. The same wear also effects the gearbox mainshaft!! Not cheap or easy but if you are going 5 speed anyway.....
Mine has been totally reliable. Despite being originally pulled out of a scrapyard in a sorry state. It has been drowned and generally abused it has always got me home. I have had 285/85/16's (34 x 10.5) on it for the last 4 years and the tall, narrow tyre certainly works better. As the trips I did got harder, I did the same swap as DB and but a Range Rover back axle in place of the Salisbury. It has a KAM locker in it to get rid of the weedy bits. This has been a fantastic mod, gained 35mm of clearance under the diff, got rear disk brakes and a locker all in one mod

)
Early 110 front ends have the strongest CVs the factory fitted. They got steadily smaller and weaker as the years went by. I have broken 1 front halfshaft in 10 years but never a CV or diff (would probably be a different story with a front locker though). The salisbury rear is very strong but hangs low and is very heavy.
Have a look at the inside of the oil filler cap. Its the quickest and easiest way to asses the health of a Rover V8. Dry and chocolate brown = sweet well looked after with regular oil changes. Black & wet = engine is tired, the head gaskets have started to leak combustion fumes into the crancase valley. Cam lobes will probably be worn and performance will be down.
Cheers
Andy