I came to the conclusion that the 4.8s was incompatible with my 486 motherboard. I sold it on for same price I paid for it so I'm happy. However, I have a generic Nakamichi SCSI drivers diskette that I am happy to sell if you are interested?
I have no idea if this diskette will work with the 4.8s and take no responsibility if they turn out to be the incorrect drivers. It does not state on the diskette exactly which Nakamichi models the drivers will work with but I can confirm that they work in MS-DOS and Windows 3.1.
I have attached an image.