I'd get a SCSI controller off Ebay, an Adaptec 29160 or similar. They cost about £200 new and I got a nice one for £20.
The drive will have a dipswitch-set SCSI ID but if this is your only SCSI device you don't need to change it; the controller's BIOS will discover the drive at startup.
Change the motherboard BIOS to boot from "SCSI" and it should work.
The drive should also work as a second HD, so you still boot from the EIDE one; this may be better for recovering old data since you may not want to boot the O/S from a hard drive that came from a computer whose motherboard was totally different. Moving a hard drive with the O/S on it and booting from it is a can of worms, and often the audio and video drivers stop working, for obvious reasons.