The Blizzard 1230-IV takes 128MB SIMMs, as does the SCSI-II module. Note that DCE Blizzards and other P5 models (ie. 1240 and 1260) only take 64MB SIMMs.
You don't actually need a driver for this - the 1230scsi.device loads itself into ROM automatically. You may need the SCSI utilities supplied with it, though, but you can get these from the net. The accelerator does not need a disk at all.
You shouldn't have any problems fitting it in a desktop case unless you buy outsized SIMMs.
Some utilities you may find useful are BlazeWCP and FBlit from the Aminet - you'll really notice the speed increase in Workbench if you use these with an accelerated Amiga.