I've previously stated I only support the original version. That said, if you place the .rpy-file in the same place as the .rpyc-file, it will replace the .rpyc-file when you start the game. At least it should.
The .rpyc-file is an encrypted version of the .rpy-file. The game builds/replaces it automatically when you start it.
I assume though, that you already tried to simply place the .rpy-files in the game directory to see if it worked, before you ever tried swapping and renaming.
PS I unpacked the original files to create the file structure, so there should be a 'chars' folder for the .rpy(c)-files, not a 'characters' folder.