If you do some research, the first pictured Skyline GTR looks like a series 2 VSPEC II NUR edition to me. Please correct if I'm wrong.
Like I've said, you can get the front bar, side skirts and pods easily - but it's those diffusers that you cost you heaps if you want the genuine look otherwise go to the places people have suggested to get good replicas made.
No, the Nismo kit - is toe Z-Tune look...I suggest you just get yourself a Nismo front bar, skirts, rear bar and pods and call it a day. That should complete the look unless you want the Z-Tune look. Google R34 Z-Tune GTR and you will have many pictures to look at to compare. Your call. If you want to do the whole Z-Tune look, you might as well get a carbon fiber vented bonnet. Again, have a look around and decide on what specific look you want.
Good luck.