mcd made the best looking cable I've ever seen:
PCB approach is still better IMO. There's no reason it can't be designed for stealth installation in the cubic underneath the HDD. IIRC the pinout in at least one of my schematics or in this illustration of proposed PCB layout is in error:
View attachment 19079
Molex outline is for reference/illustration clarity only. PCB's connection would be soldered, component and thruholes for the power cable connection of the real deal would be rearranged to keep PCB size to width of the 50 pin connector.
The stealth version I proposed would have no headers or thruholes for them outside of a single RA pair for the SCSI Bus Power jumper circuit's cutout. Edgecard contacts for IDC-34 on right and IDC-50 on left with adapter PCB suspended in between for open air insulation. IIRC it just barely fits with the one overlapping ribbon cable
Rotate PCB illustration 180 degrees: headers to Portable IDC ribbon cable connector on that side and RA header socket to 50 pin side. SSI2SD would plug directly into the adapter PCB with assembly hidden underneath the DOA OEM HDD. Alternately you could install a second FDHD in place of the HDD for a pop-top Portable Floppy duplication system. Printed FDD side panel optional.
Full (overly confuzzled) thread here for reference:
macintosh-portable-34-pin-to-50-pin-scsi-cable
edit: I'd try to make the 34-pin ribbon cable connection to the mobo look exactly like the OEM cable up to the point it would be hidden from view by the HD. Ground connection traces omitted for simplification/clarity.