So is Workbench 1.3 is still a jealously guarded bit of commercial software? Or can it be downloaded onto a PC from somewhere and then be written to an Amiga-spec floppy disk? I assume this is where RAWrite may come in handy.
You cannot download it for free, I'm afraid. If you want to emulate an Amiga as well then
Amiga Forever comes with the images, however putting them onto an Amiga disk wouldn't be nice; the Amiga has a more flexible floppy controller than the PC, with the result that the PC cannot write to Amiga disks. Unless you've got a working Amiga that can read PC disks, then it wouldn't be possible. If you just want to check that the systems are working, then you could grab any bootable disk, like a demo, but again you wouldn't be able to write it to disk. I'd have thought that you'll need to go looking round for the physical disks.