Why not the new Hasselblad back? That way you can use the leaf shutter in the V-series lenses without an extra cable, you get a modern LCD screen on the back for 100% zoom, focus peaking, etc..
Anyways, didn't mean to derail your thread. It might be worth your time to reach out to a dealer like CI and see what their inventory looks like as far as used digital backs if you're set on Phase. Good luck!