I can definately use boot disk for my 128k. I need to check the disk I'm using to boot my Plus and see if it is 400k floppy or not. I know I tried it in the 128k and it wouldn't boot. It may be that it just doesn't work anymore, but it does boot up to the sad Mac icon. I'm assuming if it gets that far that it will boot with the proper disk as long as the floppy drive is OK.
I have a lot of other floppy disks that came with the 128k with various games and stuff. But I don't know how I could get an OS that I download on a floppy.
Also, the 6.0.8 OS looks like it is for 800k disks. So it will not work for a 128k?