I reckon you're right. There was a similar thread recently about whether it's best to invest in a UK spec or a JSpec. Whilst a mint JSpec might beat a shoddy UK spec, a mint UK spec is surely the best bet, and that's what you might have there (check the underneath for rust).
With rare cars, there comes a choice whether you try to keep it mint to maintain its investment value, or enjoy driving it regularly. Unfortunately these tend to be mutually exclusive choices. If I were in your position, I would garage it and drive it on occasional long trips, not on trips to the Maccy D's drive-thru 2 miles down the road.
If I was really lucky, I'd buy another, less-rare, supra as a run-around, so I could still enjoy the buzz of driving one whilst not having to wring my hands with worry every time I wanted to park in Asda for a pint of milk and some Pot Noodles.