JDW, is your Hyperdrive in running condition? If your Hyperdrive has an MMI or Miniscribe drive, it would be a miracle if it still spins. 
NEC 20 MB drives are the best bets of those early 3.5" drives. I have a couple of old NEC MFM drives from that era which still ran last time I fired them up.
Somewhere out in the barn is a MicahDrive chassis, which was a SCSI internal HD for 512s. Micah worked out an internal drive which didn't involve drilling holes in the Mac chassis, and held the drive, controller, power supply and fan all in one piece. Pretty good shock mounting, too. The drive still worked after PanAm dropped my Mac hard enough to break the case on a flight from Paris. I'll dig it out and take pictures.
I simplified my own internal HD some years ago when 2.5" notebook drives became available. I yanked the MicahDrive and stuck the laptop drive to the top of the floppy with bits of foam tape. My Mac still boots with the Micah icon, tho.
NEC 20 MB drives are the best bets of those early 3.5" drives. I have a couple of old NEC MFM drives from that era which still ran last time I fired them up.Somewhere out in the barn is a MicahDrive chassis, which was a SCSI internal HD for 512s. Micah worked out an internal drive which didn't involve drilling holes in the Mac chassis, and held the drive, controller, power supply and fan all in one piece. Pretty good shock mounting, too. The drive still worked after PanAm dropped my Mac hard enough to break the case on a flight from Paris. I'll dig it out and take pictures.
I simplified my own internal HD some years ago when 2.5" notebook drives became available. I yanked the MicahDrive and stuck the laptop drive to the top of the floppy with bits of foam tape. My Mac still boots with the Micah icon, tho.