Actual dealers (most of the time) have some sort of integrity. I bought mine sight unseen from a BMW dealer 1200 miles away, and the truck was extremely well represented and the process was painless. Used car lots on the other hand are a joke.
For some reason, I've seen more and more online over the last few months that the LR4s are unreliable. I heartily disagree. I think the issue is that, as they get older, the fourth and fifth owners are buying them and getting ones that were not maintained.
If the timing chain job has been done, the other major engine maintenance is the front and rear coolant crossovers and water pump. Have that done the same time as your timing chain. You might also think about having the fuel injectors really looked at and cleaned or replaced.
The other big maintenance things have to do with the air suspension. Either an air strut or the air compressor. This is no different than a standard vehicle, though, whose struts need replaced at around 100k miles.
Change all the fluids right when you get it. This includes the transmission fluid.
Should be good to go after that, so long as the previous owner at least did the minimum maintenance.