I believe KS 1.3 only supports OFS and is not capable of reading FFS floppy or harddisks. I believe FFS didn't come out until 2.0. I can rember FFS floppies could hold several Kb more on a disk than OFS and I wished I could read them on one of my KS1.3 machines.
edit: Found this...
"A replacement for the Old File System that allowed more to be stored on a disk. On Kickstart 1.3 this was stored on disk meaning that it was impossible to boot directly from FFS disks, but since Kickstart 2.04 it has been stored in ROM since version 2."