[dnanian]

If you erased the drive with SuperDuper!, it's likely the problem is that the drive wasn't formatted to include OS9 drivers (SuperDuper, being an OS X tool, erases and does not install OS9 drivers on the drive). To work around this, I'd suggest using Disk Utility to erase and install OS9 drivers, and then use SuperDuper!, in Smart Update mode, to copy the data to the drive.

It's also possible that you need to re-select the boot volume, which is no longer known by the system's PRAM. Try booting with Option held down, and select the boot volume. You might also be able to clear PRAM with Cmd-Option-P-R during boot to get it to re-select the drive...