I used a SCSI Zip for quite some time, alternately plugging it into my former PC (with a NCR810 card) and my A3k. Interchanging disks with the IDE Zip at work was no problem either (disks in FAT format).
I don't really get what you'd want the parallel SCSI adapter for - it's easier, cheaper and faster to either get an IDE Zip or an old PCI SCSI adapter for the PC.
