You'll need something along these lines
Nissan 350Z Kit 2006-up, chassis sizes E/DD at Crutchfield.com
*Note that's for the 350, but it gives you an idea. Probably works for 370 as well, but I'm not sure.
The wiring harness can be picked up online, or your local car audio shop likely has some. I'm not sure if any site sponsors sell them or not.
Are you going single din because you have more options available that way? If you can find a double din that you like, they look better in a double din slot to me.