It's nice to know that with the high compatibility of 2K12 and 2K13 files we can convert a lot of the 2K12 stuff easily and bring them over to 2K13. However, it's one thing to do this for yourself, and it's another thing to release the edited/converted works of others.
If you want to release an edited or converted version of another modder's work, be it a Cyberface, an Arena, a Jersey, or whatever, you should ask for their permission first. Not release and then ask for permission, ask for permission FIRST.
Although most modders shouldn't mind to see their work converted to 2K13 with proper credit, some of them don't like it when people re-release without permission.
Any reports of stolen work or releases without permission will be handled immediately resulting in the deletion of the files and/or the thread. Repeated offenses could lead to an official warning, or even a ban. So keep that in mind, and play fair.
P.S. With that said, starting asking for permission and converting! What are you waiting for?