No one bothered to tell you that 1.3 is very likely the newest OS you can run from Floppies! Even 2.0 has too much to be run well from floppy disks only.
The best bet is to get the 3.1 ROM, but you'll have to get a new hard drive - Get a 2091 card, and a SCSI hard drive. Then install OS 3.1 onto the new hard drive. Even that is a real basic system, but will work fine.
BTW - chances are real good you have a 1.3 ROM in there now.
