Not sure why, but my CCK Number fields are only showing up as options for the Label, and not the "Value-x" selection list. I'm using relationships, but I don't think that would be an issue.

Why not just remove the limitation of forcing fields recognized explicitly as numbers. Have some faith in your users being able to figure it out. First instance, the views_customfield module allows you to derive numbers from non-number fields, or from combinations of number fields. Preventing your users from using the fields they want to use comes across as slightly over-bearing :)

Very ambitious and cool module though! All the best!