Well I got it to boot once...

...I had a Sonnet Crescendo G3 in there that seemed to be one cause of the problem. I also had to switch between the 2 SCSI connectors on the Logic Board, from the "Fast SCSI 2" slot, to the "SCSI-1" slot. That seemed to work.

I popped in a 604e 150 MHz card that works just about every time. The Crescendo is hit or miss. :-/