I want to buy a 1992 S8

I have test driven a S8 (1992 V8 4.2) I have noticed a few possible problems, Could some one out there please advise me. The problems are thus:-
1) The engines smokes on idle when hot. There is no smoke when cold and when driving, only on idle. The owner is telling me that the car has stood still for the last 6 months and that he had the cambelts and ALL 32 valves replaced 8 months ago.
2) No matter what the tempreture or speed the oil pressure gauge is sat at 5bar and just over. Could this be a faulty gauge or something more sinister?
3)The brake pedal has excessive travel. The owner told me that ALL pads were changed 8 months ago and the system bleed correctly.

The guy was asking €6000 for this car. I have offered €4000 which he has accepted. Is this car worth the €4000 with the above faults.

Many Thanks

Simon