As you say Ed, no dedicated pofile for the 645Z. But countless other options that you can choose from and save that as your standard profile. In addition based on the color editor you can create your own.
Who knows - if you choose to fake as a Fujifilm 645 that seems to use the same or very similar sensor to the 645Z‘s you maybe even be able to use the Fujifilm‘s Film simulations?
Would be interesting to see if this would work and how iit looks concerning noise ...
... such a huge playground for someone who likes such.