Well, I'm happy to report that both the SCSI upgrade that I repaired and my home made cable work perfectly fine with a regular older Apple ROM HDD.

So it looks like it's the SCSI2SD that's causing the problem.

techknight said:

When you use an SD card, or any flash memory for that matter, you need to align the partition on the 1024 boundary.

Click to expand...

Do what now?  I have FWB Hard Disk Toolkit 2.1, Lido, and Anubis Utilities.  If any of those can do that, then I'm all set.  If not, then I can't.

It's still pretty darn fast even with an old HDD.  Booted just as fast as the SCSI2SD with System 2.1 as far as I could tell.