I’ve got two MagicBus cards (Mac SE PDS, one "empty", one with an 68030 accelerator), and two Radius graphics cards matching. But - no cable in between. Looks like a UW-internal SCSI connection, but apparently seems to have 60 pins, not 68.
As far as I understood those radius boards there was no cable for that bus port but instead a secondary card that is supposed to go on that slot like these photos of a board I saw on ebay. I'm not sure of their compatibility tho. This is just a 2 page display board that also does not have the video cable with it.
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edit: Here's the only other photo I could find real quick of the whole set together I'm assuming this is like one that you have.