Could I mount a Mamiya Digiback?
Do you have any lenses to sell with it?
How much would shipping being to Brooklyn, NY?
The sliding back adaptor is machined for the Hasselblad V mount. I rather doubt, although I'm not certain, that there are Hasselblad V plates available for Mamiya digibacks.
I do not have any lenses to sell with the kit.
It would probably cost around $75 to ship the kit to Brooklyn via FedEx ground.