I love the NSX concept - great cars.
I have repeatedly blown them off locally with my turbo Fiero, which probably has made a couple of them wish for a turbo - and if I owned one, that's the way I'd go. The LS7 is around $13K and that transaxle is big bucks too. That was a cost no issue conversion.
The stock engine can get twin turbs for $8K and while it adds only 120 BHP or so, the car will be very quick (1/4 around 12.8) and that solution just feels right unless you are a 'give me a V8 or give me death' type (and there is certainly no shortage of those around).