Check the cills on both sides, inner and outer. Just run your hand along the bottom of the cills from front to back to feel for any holes or weld patches. With the inner cill, just stick your hand around the back of the 7inch section of cill in front of the rear wheels and again check for holes, patches or heavey corrosion. If these are all good and it runs sweet then it's a good one.
The cam chain should NOT rattle badly or continuously, sometimes if they have been stood for a week they may rattle just after starting for 1 or 2 seconds. Any longer than that and the engine may be very low on oil, or the chain tentioners are worn. In any case if they rattle like that then don't touch them, walk away and look at another one. It's an expensive job to buy chain and tentioner kits. And if you're wanting a daily driver then you won't want to have to start messing around with a bad one just to get it running right when you can just get a good one to start with. (Y)
As for the age thing; my friend has a 93' 1.0L "L" 4-door, it has over 160,000 miles on the clock and it's all origional under the hood, even the chains and tentioners have never been changed. Aside from a floppy gear-stick and a noisy thrust bearing it runs lovely. So i think the "it happends to all of em with age" thing is a myth.
Good luck, hope you find a gem out there. (Y)
hope you get one soon 
