Yes I think the 7720U model is the one you need. The other ones (with the UW SCSI) are ideal for the Cyberstorm because that's the SCSI type it has (I have one with a 7720UW and it works just fine).
About OS4.0 support for the Blizzard PPC SCSI, you're right. There is no support for it and according to what was said during Amiwest, that situation won't change with OS4.1 for Classics.
Regards,
Efren
