Just keep in mind that to use Kodak Pro Back on your Hassy, you require a custom made Capture Group cable, which is really hard to find now days + it will be a bit uncomfortable to shoot with your camera handheld, cause the release button, which you need to use - to take a picture, is located on that custom cable.
You better watch for CFV16 and P20 back or get one 555ELD to use it with Kodak Pro Back, cause it doesn't need any extra custom cables.
Good luck with search!