According to reviews on CellarTracker this wine is drinking well and at its peak.
What this particular bottle is like depends -- as Lisa said -- on its provenance. How has it been stored the past 30 years?
The seller won't guarantee it - that's not unusual -- but unless they offer some convincing evidence of its provenance I suggest you pass on it.
Another factor is that this is a very old wine and even in perfect condition it will taste like an aged wine. Many wine lovers know and appreciate the changed taste profile but if the recipient isn't used to drinking old wine they may be very disappointed.
If you use the money to buy a case of good wine then you can open a bottle now and on the anniversary over the next 11 years.