TO BUY OR NOT TO BUY? 2000, Monster 600 Dark 9,000 miles £1000

My friends boss has had his Monster sitting in a garage for the last few years. it is in great condition but does not have MOT or Tax. It has had 2 owners but has a full service history.

It was also stolen but returned with the only damage being the mirrors which have been replaced. Does this effect me in any way?

I have only seen pictures but I am going to see it next week.

What sort of things should I be checking for? i.e. chain, sprockets, tires, oil leeks ect?

I was thinking £1000 was a good deal but am afraid the bike will need a full service as it has been sitting for so long? If so I hear it is around £400?

It would be great to get any thoughts or professional opinions.

Many thanks, Stephen