R80G/S - advice on buying one

[ancv]

Hello all.

Need some advice.

I'm buying R80G/S. I allready read a lot about it on the internet, but never ride one.

Now somebody is selling it and I think it's great opportunity. Here is the link to his ad: http://www.avto.net/_MOTO/ad.asp?ID=5967300

few details about it:
year: 1980
mileage: 72.000 km
second owner

It looks good – I think almost everything on it is original. He owns it for 8 years and is a second owner. He bought it for around 2.000eur in 2004 in Germany. The bike was more or less in garage. He made just about 8.000km. The problem is that the seller doesn't let me ride the bike.
So I ask myself what could go wrong if I buy it (how do I know that the frame isn't bent, that suspension is ok, etc.)? Is it worth a buy?

I would appreciate any advice.

Thanks