As far as just splitting the file, it's too big. You probably already realized that:-). The A2091 eprom files are 8k each (2) and the Guru Rom for the A2091 is 32k, so the need for the additional address space.
Speaking as someone who actually had this and sold it, I wouldn't actually go to too much trouble to get it working. My 2000 is much happier with the SCSI controller built in to my Blizzard 2040. The Guru/A2091 combo wasn't completely without trouble as I remember. In my opinion locating a better controller would be a more efficient use of one's resources, unless you are just doing it for the sake of the project:-D YMMV.
Jeff
