Alan
A great choice, I own a number of vehicles but the lightweight is one of my favourites... Apart from what you have already noted you also need to think about what you want to do with it ie do you want it to be as original as possible, or are you happy with a few sensible mods. For example if you want to fit the proper tyres (6.5 x16 goodyear xtra grips) these are hard to find and expensive. Also are the sidewalls cracked at all? Also what mods has it had, is the interior original is the data plate in place? The original miltary style headlamps can be hard to find if theyve been replaced. Most spares are cheap and readily available but you might use a lot of them!
What is the seller like - ie are they an enthusiast as this gives an indication as to how good their maintenance might be (but not always!). How much use does the vehicle get? The more the better in my experience, it is amazing how many oil leaks, squeaks and rattles resolve themselves with use. What is the wiring like? Do all the electrics work as they should? Does it have the original split tailgate? And the original flat ended hubs? If you can get a test drive does it pull to one side on the brakes? This could indicate a brake problem but might also indicate a hub seal leaking on the shoes (is there any oil on the rim if so) easily fixed usually but good bargaining point.
The half ton military landrover by Mark Cook is an essential book to have before you buy. Although it doesnt give buying advice it will show you what they should look like and help you understand the different models.
As with all landies the 4wd gubbins can seize if not used for long periods so make sure you can push down the yellow lever, and pull the red lever back and forth without problems.
Although they are getting a little rarer, they still come up regularly so dont feel you have to go for the first you see.
Basically though just enjoy it, they are fab little vehicles, the best landy by far (in my humble opinion)...
Cheers
Timbo