Telling if ED has genuine 90,000kms?

[TuMor]

Im gona see a car today for my brother, weve been looking at EB's and ED's with average kms on the clock. Now this one boasts a genuine 90,000kms on the clock, immaculate condition...so on. Owned by an old man from new, garaged most of its life, used to tow a caravan sometimes.
My EA was owned by an old man who did alot of towing, it had avarage kms...i dont think that sort of history is bad compared to a family car, or one owned by a young bloke.

Back to the question, what should i look at to see if that is genuine kms, on the clock and not say 190,000kms winded back to 90,000? I was told that its just had its first headgasket replacement...
Im expecting this car to be extremely neat and tidy, perfect all round...but i need to be sure that this history is true, because it is more expensive than a normal ED.

Any thoughts? (the car is not from a dealer, private ad placed by the old bloke)