Here are the latest QuickSpecs for the HP G1 Z Turbo Drive. I wish HP would put a G1 in front of all their references to this, but they do not. Note you can use this version, the AHCI version, on both the ZX20 and the ZX40 generation of workstations. The G2 is officially supported only on the ZX40 generation.
http://www8.hp.com/h20195/v2/getpdf.aspx/c04328813.pdf?ver=5
See page 3 for the latest option part number. I'm not sure, but I think all G1s had no heatsink and all G2s do.
Best price I found for my Predator M.2 kit was straight from the source at 155.00 USD.
Why use that instead of Z turbo? G2 cannot work on a Z600, period, as explained earlier. G1 has never been shown to work on a Z600. I wanted something that I had at least a hint that it would work, and the two sources I noted were top notch.
It would be great if you would take on the project to see if you can get the HP G1 to work on a ZX00 generation workstation. That would be a valuable breakthrough if you can pull it off. The HP gear is always what I'd like to use over all others because I know the quality of the engineering that is behind it.