Here is my positive statement: Sounds like a great project.
Let us know how it goes, you are probably the first to do it. (there is only a couple of hundred NSX'ers that take on such projects...unlike the Civic crowd where there is several hundred thousand on any given day doing stuff like this.)
You are asking a lot of questions in one go around (details below).
I was wondering if it were possible to purchase the 4 piston brembo front calipers from him and just buying the 12-13 inch rotors
Sure.
or is this gonna be way more fab work than I want to jump onto???
I don't know what you are willing to jump into, this is not a bolt on project. Not difficult one either.
1. You will have to fabricate some brackets
Do it here:
http://emachineshop.com/
2. possibly fab up some brake lines.
Check your local or online hose maker for this, very common.
3. possibly modify the front/rear bias
Any speed shop will have the parts....many posts here on 'prime on how to do it properly.
Easy project: just takes discipline, time and a bit of money.
Drew