Part number for the shell is 51257, its due out yesterday in Japan. The shop i use in Japan already have them.
As for handling, what class is that for? In the UK thestock class (TT01's on kit radials and RS540 sport tuned motors) the NSX is king. I did use the Nissan Fairlady Z (GT500 Version) a bit last year which gives more turn in, but has a less predictable rear end, i would have thought the SC430 would be a bit more like that. This is mainly down to the fact we have to use the kit supplied wings rather than hop up versions in stock. On decent tyres with a proper wing, then i am sure it would be a bit more forgiving.