The flange distance isn't the only (nor even the primary) factor that negates a Cambo Actus/Pentax 645D-Z combo. The dimensions of the camera body itself will not fit on either Cambo Actus Mini or Actus DB, and if Cambo did produce an Actus just for the Pentax, then it would be a much larger view camera, which somewhat defeats the point of the Actus.
However, there is a Cambo product that has precedence for this line of thought, and that is the Cambo X2 Pro.
https://captureintegration.com/cambo/cambo-x-2-pro/
Interestingly, once the Actus began shipping, I had some clients who liked the concept, but wanted to use medium format digital backs, and not just with Schneider/Rodenstocks. Since the Actus DB only has room for a digital back to mount and rotate/operate (meaning no room for a camera body), the requirement is a lens with a manual shutter mechanism, which rules out medium format lenses.
However, the X2 Pro does allow mounting the Mamiya/Phase One AFD/DF camera bodies, and then you have a camera body to use as a shutter, which enables Hasselblad V lenses, Mamiya RZ, and so on. Perhaps an interface for Pentax 645 could be produced for the X2 Pro, or perhaps there is some future product that could utilize a medium format camera body like the X2 Pro does with the Mamiya/Phase One bodies. It's all about the level of demand.
Steve Hendrix
CI