Hey Nick, yeah just OFS/FFS as I don't have any SFS or PFS disk images to test.
I want to add real drive access later too.
Once all that works, I'll see about supporting other file systems.
To be honest the real fun is making a "workbench" clone to access them... there is also a 68k emulator in there too... just not doing anything at the moment 
Are you going to put the source on GitHub or some other public place. I understand if you might not want to, but learning is awesome. I'd love to see how you did all this.
I can't wait to download a build and try it out.