Hey mate
Nismo 480 are direct drop in.. I currently have Blitz 525 (thanks darrin) Which require a lift for the fuel rail however flow alot higher.
Tomei Pump is cheaper buy it, please contact Performance wise for both as he is cheap. I used him and recommend him.
Everything else seems right however Id add on a turbo (perhaps talk to evil wevel what hes running, highflow isnt as good supposedly) Id also add on a Oil cooler so everything doesnt over heat. They are costly but well worth it.
While you there do a 100,000 service so buy yourself a timing belt and kit including water pump as it will save you a few $$$ down the road.
Spitfires will make sure you fire every time and you also would look at a z32.. it will be able to measure air more acurately and wont max out.
Clutch wouldnt hurt.
Enjoy
Buy everything in my sig basically (the awaiting install bit) minus the bov its gay and drives like ass