Currently wrapping up a full playthrough, making suggestions on what to do with each level, and categorizing them by how much work they need. I'm providing the links to each post here, for easy access. Keep in mind they're just my personal suggestions. If you're looking for a level to refurbish but aren't sure which to pick, consider consulting these posts, and of course playing prospective levels yourself before working on them. I hope this is at least somewhat helpful.
Also, keep in mind this will become more and more outdated as people claim and fix levels.