Oh, man. My brother is there now - demoing his Mac-based SDR "Heterodyne". I told him to be on the lookout for some Mac parts for me. Sounds hopeful.
Is your HD 20 an MFS floppy port model or the HD 20 SC SCSI model?
Is your HD 20 an MFS floppy port model or the HD 20 SC SCSI model?