DLE 30? I've been helping my flying buddy with his 1/4 scale Hangar 9 super cub and it flies like a champ with a G23. But it is probably a few pounds lighter than your Cub. I've seen a couple of the Kalt engines some years ago and with the right prop they seemed just about as powerful as the more modern Zenoah engines. Try an APC 16X8 on it.