I've been working a lot lately with demystifying camera color, through writing a camera profiling software (DCamProf,
http://www.ludd.ltu.se/~torger/dcamprof.html , which is free and open-source). I recently completed a DNG Profile for my Hasselblad H4D-50 that I think is on par or even exceeds the look of Hasselblad's own Phocus, but I've only used it for a brief time yet so I may do some further adjustments.
I'm sure it's possible to make a good profile for the 645z too, especially if you have a look you know you like which you can be inspired by when designing your own profile.
If you just want an accurate profile it will be even simpler, mostly mechanical profiling work, you just need to apply some judgment when making accuracy/smoothness tradeoffs.
I'm working on a tutorial so it shall be a bit simpler for others to make profiles. There's already reference docs with the software of course, but I know many would prefer to have a finished "recipe" and it's exactly that I'm working on.
I think handing out the power to photographers to make their own high quality profiles is much overdue... I hope to be able to contribute to that, but I need a little bit more time to make it more accessible to non-experts