I made OS floppies for my Mac Classic using a PC running Windows XP and a USB floppy drive. I got a raw image, and used rawrite to write it to the disk. It boots fine in the Classic.
You can also download Stuffit Expander for PC so that you can extract the images from the .sit files, if that is the file type you have. I have original system floppies for both system 6 and 7, and if I can legally do it (can I?) I can make image files from the floppies so that you can write them back to floppies using rawrite (or similar) and a PC.