You won't need spacers to fit the later series wheels on an early NSX.
Learn lots about
wheels &
Tires at these links
You can fit 17/18 combo with
little more risk to the wheels than there is for std. - std 16/17 are 45 & 40 series aspect ratio tires respectively compared to 40/35 for 17/18. A pot hole that will damage those will most likely also damage the 16/17's. Now the 15/16s are a little taller tire at 50% F & R.
If we consider some front wheel options:
Stock 15" dia rim has 23.1 dia tire => 8.1"/2 = 4.05" of sidewall between edge of rim & road (In reality less when weighted by car load)
Stock 16" has 23.6" dia tire => 7.6"/2 = 3.8"
Typical 17" has 23.8" dia tire => 6.8"/2 = 3.4" sidewall.
Now, you can see all the tires, despite their different wheels diameters are within a 0.7" range on the tire diameter (or half of that for the radius which would be the difference in ride height) - quite acceptable really & will have minimal effect on the TCS. By changing the aspect ratio, it is possible to keep the final outside diameter similar even though the rim size is changing.
As far as the tire sidewall height goes i.e. the protection between a pothole & your rim, there is less than 1/2" difference between the stock 16" or after-market 17" tires. Remember also that the new 02/03 NSX has 17" front wheels now.
Having said that you will definitely "feel" the road more with 17/18's, especially compared to 15/16 50 series tires. However I myself run 18/19's with 35 & 30 series tires respectively & still find the ride acceptable & with no TCS issues.
You will find many examples of options in styles & sizes if you research this wheel/tire forum here on NSXPrime.
Good luck with your choices.