If I recall, it was somewhere with the introduction of the Ultra320 SCSI drives that they started dropping backwards compatibility with older and slower SCSI buses.

I found this out first hand when I was trying to put drives in my Silicon Graphics Onyx and they were not showing up even though they worked fine in my later Origin 2000.

Considering that at the very least you require a mac with an 040 and 7.6 to partition and boot drives larger than 4gb, I would strongly recommend you look for a different drive. I'm sure you can find someone willing to trade drives at the very least. the IIfx is a very fine system.