A more practical application would be to use the Plus as a head unit and then connect an external SCSI drive connected to it, and another Mac with a hard drive, like an SE. Boot up the SE, and interrupt it. Then access bothe hard drives from the Mac Plus. Then when the Mac Plus was turned off, both HDs would be accessible from the SE. But you'd still need active termination between the external drive and the Plus, for which there were switchable terminators, some of which were alleged to allow hot swapping, though I don't think they were particularly reliable.

If the idea is to use a SCSI drive as a shared network drive, then attach it to one Plus and access it via an EN/SC from the Other Plus. Youcould also access it via AppleTalk, but that sort of defeats the purpose of having the speed of SCSI.