Compression rings don't conform to any standards. They're an internal part of the headset, and so are brand specific. That said, there are many different headsets that share parts. Start by searching based on the specific brand and if you don't find one, look for similar looking headsets from the same country, which hopefully will be made by the same people, or at least ones who share vendors.

I don't know that you'll find one new, so the best place to look is in the scavenge boxes that many old time mechanic keep of parts saved from repairs. Also you might find something at a co-op where it might have come off a relic scrapped for parts.

BTW- how badly did you "sort of" destroy the original one. There's plenty of latitude in condition where they'll still work. As long as you have 3 OK areas spaced roughly equally, they'll properly center and support the cup (think of a Tri-pod). Before you go nuts looking for a replacement, see if you can file off any high spots, so then headset can rest on the original surfaces.