Well it seems the old Adaptec SCSI controller's BIOS will not allow booting from a CDROM. The Motherboard BIOS was designed back when 212 meg was a *huge* disk drive.

I've obtained a 'less obsolete' ATX formfactor box [don't know the CPU, but its likely much faster than the P133 in the other box]

Now all I need to do is scrounge some RAM [probably retail] then I should have a working x86 box - this one should boot from CDrom, sidestepping the original difficulty in generating a boot floppy from a .img file on a Mac