Darn Z4 and PowerFlyer! I'm grappling with similar problems at the moment, but I can offer the following:
1. The PowerFlyer replaces the Amiga's scsi.device with its own. If there are devices on both of them, one will be renamed to 2nd.scsi.device
2. My Z4 board hates my Blizzard060 (Not all Zorro cards can be detected), and refuses to work at all with a PowerFlyer ZIV connected.
3. I think (not certain, though) that you *must* use AllegroCDFS with CDs on the PowerFlyer. Asim is, unfortunately, vastly out of date now. Replace your CD0 DOSDriver with one from the PowerFlyer disk.
To be honest, I'd recommend switching completely over to SCSI on the BlizzPPC, or putting up with motherboard IDE. Then you can get the BVision back.
If I can be of any more help, let me know.