Try finding a local bike co-op or somewhere you can take your freewheel off. For a SS you'll be putting on a bmx hub most likely with a circa 80's Peugeot. The freewheel threads onto the hub and once it's off, all you do is spin on the bmx hub. The chain is likely pooched, so get a new on and set it up on the existing rings. What size rings do you have right now, if you can tell?