In order to use any SCSI unit on your 1200 you need a SCSI controller. You just can't connect your 25 pin connector from the SCSI enclosure, it has to go into a 25 pin SCSI connector. The parallell port and the SCSI standard are NOT pin-compatible, you'll probably burn some circuits if you try to connect them.
If you want a SCSI controller, I can personally recommend the Blizzard 12x0IV accellerator with its optional SCSI controller. If you can get hold of one of these, you'll gain an extra 25 pin d-sub contact at the back of the 1200 which you can plug the SCSI enclosure into :-)
Other alternatives are the Squirrel SCSI controller etc, but the Blizzard is IMHO the best alternative.
