A "1MB" floppy is the same as a 720kB, is the same as an 800K floppy...The 1MB designation refers to the unformatted capacity.

Just to back up a bit, realize that the Disk Tools floppy that comes as part of a system installer disk set is a bootable disk. For System 6, it is a single 800K floppy. Just use that. The entire set is available as a free download from Apple, so you can start with images from the source itself.