Bias ply is older....though not to say its not still in use....a lot of racing tire at club racing/amateur level are still bias ply...
I voted light, but really should be case by case I guess....light modification is what I'd do to my own car....
In the case of what NSX is asking, IMO that entirely depends on what you want to do. I love the newer style of these Pro Touring muscle cars, basically restored body work, updated/upgraded chassis/brake/powertrain technology. IMO thats like the best of the 2 world, which preserves the classic styling(more or less), but with cars that drives like a new car.
Some people prefer to fix up the old cars like how they are built, while some might want to make the car just drives better, a few of my coworkers have old muscle cars that they drive in the summer, and one of the thing most does is to give them more modern brake(maybe not modern big brake kit or something, but simply drum-to-disc conversion), if you want to actually drive them, something that makes it safer is probably not a bad idea....of course, if you are in it to win concours, you probably should keep stuff original...
My car right now, its mostly stock aside from chip tune(performance) and a louder exhaust(boredom). Season appropriate tires are a given, and I have upgraded brake caliper bushing(feel, pad wear) and track specific pads for tracks(temperature performance). Next year I am thinking of changing out the struts to some for performance minded ones(just struts, keeping stock spring), and maybe a rear sway bar. Not looking to alter right height at all, just maybe a bit more body control for autocross and track days....
University of Toronto Formula SAE Alumni 2003-2007
Formula Student Championship 2003, 2005, 2006
www.fsae.utoronto.ca