Alright here is an update.
I went down to HKS to test and exhaust (I'll have a seperate post on that later with some pics). They have thier own Z and GTR. The Z had an incomplete partially prototype turbo system on it. I say partially because the kit is using parts from thier "set up kit". I'll explain what that is below. It wasn't complete as it had no finished I/C or intake piping yet but it did have cast manifolds, turbos, turbo exhaust outlet housings/pipes, and front mount intercooler cores mounted up. The intercooler had some piping and the cores were separate (one for each bank with thier own in/out but mounted together similar to HKS's Z32 front mount if you've ever seen that kit.
At this point there is not much else to share except that it is still and engineering excersice with no sure answer whether they'll make it or what the cost will be. Judging by the amoun't of parts used I wouldn't expect it to be really cheap though.
If you have plans to do a custom turbo kit they make what they call a set up kit. A set up kit is basically the major components to get started, but no vehicle specific piping and engine management. Those parts would be left in the hands of a capable shop or installer if you have the skills. In fact the set up kit is that same as the VQ35-HR kit. I was told that the compressor outlet pipes will not work on the Z34 but most of the rest will work. Here is a pic from thier site that shows a VQ35DE set up kit, I was told they look very similar:
Here is a list of set up kits with different turbo options from thier site:
HKS VQ Set Up Kits
All I could get on the GT Supercharger kit was it's being considered but no ETA right now. I was left with the impression they are going to look at it because my friend mentioned what a pain in butt a mounting location would be.
Sorry nothing more concrete for you guys except it looked bad assz lol.