Welcome to NSX Prime! We can definitely help you find the right car.
Short version: that NSX is significantly overpriced. Real value is probably around $60k.
The corrosion on that NSX is normal for cars that lived in a salt-water environment whether in a costal area like Japan or in a state where they use salt on the roads in winter. Those bolts can be easily and cheaply replaced. It doesn't tell us much.
A good place for you to start is
Prime's NSX valuation tool, which gives you some of the best data for the car's current market value. It's based on US data, but a RHD 1990 JDM car like this one can be approximated. Currently, the average value of an early pop-up coupe is about $68,000, assuming 100,000 miles. On your car, the mileage is unknown, but 100,000 is a good number to use for a very early NSX at this point. The value can go up or down from there. In this case, it probably goes down since the car is RHD (less desirable in the states), has unknown mileage, unknown maintenance history and is modified.
If the car has an LSD, then the trans has been opened. If it was done in Japan, I'd feel better, but there are very few people left in the US than can competently open and modify a NSX manual transmission without messing something up. Also, the condition of the engine would be informative. What are the compression and leak down numbers? Sea level warm compression should register above 200 psi and ideally above 220 for a truly healthy NSX engine.
Lastly, during the past few years we have become aware of unscrupulous people importing RHD NSXs from Japan with undisclosed crash damage (sometimes severe). Basically, the damage prevents the car from being registered in Japan, so they bring it over here in the hopes they can tap into the JDM car craze and find an unsuspecting buyer. Before laying any money down, I would have some basic frame measurements done to at least confirm the unibody and frame are square and inspect the side sills and front/rear beams for evidence of cutting, bending or welding.
Finally, you're going to have a tough time registering the car with the NYS DMV if the mileage is unknown. They may have exceptions for RHD cars (not sure), but they are really strict about the mileage.
Knowing all this, I'd pass on this one. FWIW, it is possible for a 1990 NSX to be worth $90,000 (or more), but that would mean a fully stock car with good paint, a fully documented maintenance history, no major body damage and a healthy engine/trans.
