They are. I've bought rings a couple of times, which is why I now have an abundance of screws.
The modern style rings are great, so I don't think you'd regret the upgrade. Just depends on how original you're trying to keep it.
I don't really care if they are not the orginal rings. I'd rather have something trivial like pickup rings look nice than try to preserve ones that are in poor condition for the sake of keeping the guitar truly all orginal.