User blog comment:22. excalibur/Possible Mod?/@comment-1466854-20131111220143

If you get a corruption world, you may be able to use a map editor to switch the new ores to the old ones. Might even be able to use it to switch all crimson to corruption. Realistically though, I find the new ores produce better gear, I'm not sure why you'd want to ditch them.

You could also just get a clentaminator and a pile of purple solution from a corruption world and go nuts on the crimson with it, though that wouldn't quite be a perfect solution.