Which Supra specialist has the car been taken to?
Have you spoken to them to confirm what the seller is saying?
It might just be me but you sound like you have already made up your mind about this car. You seem to be ignoring specific basic questions and realistically how hard can it be to contact the previous owner these days or his “mother”.
If it was me I wouldn’t be paying out 25K on an unseen car end of. If there is no friendship involved this is purely a business transaction.
The skirts and spats haven’t been removed so how do you know the bodywork underneath isn’t rotten?
My advice is to get a through independent inspection carried out on the car. Make sure they include a compression and leakdown test.
On top of the above I would want videos with good lighting done in the dry of the underside of the car, the outside of the car, cold start, engine running, exhaust with someone revving the car.
I assume you have read the PDF here - http://www.mkivsupra.net/vbb/showthread.php?67644-What-to-check-when-buying-a-Supra
Any noise or excessive wear on the rear suspension components due to the wheel offset and rubber band stretched tyres?
What is the cars history? By this I mean provable documented history on paper, ideally a folder of receipts.
Have you seen any?
Is there any?
Any maintenance been carried out on the car? Going with the above you want recipes showing mileage, service history, fluids and parts used et cetera.
Have you looked at the car I linked to in my other post?