Yes, there is the PCB version without any enclosure. It is 88 Euros than instead of 112. And there are the different connectors, for various attaching situations. See all the "Gigafile Adapters" in this overview: http://shop.inventronik.de/store

So yes, it should fit into the Powerbooks as well. It should even be possible to mount it internally in diferent ways. Perhaps as Floppy replacement, or in PDS "Slots" etc.

I really need to test it with System 7. But the Intech HD Speedtools are working with 7 anyways, so it is at least usable with any Mac that has SCSI.