I never saw a Cub at any size that could match to Cox engines. They all seemed to be wimps, although the 14 was easy to start and easy to get a needle on, it was more like a Cox Queen Bee in power output (a Medallion 09 would blow it away). I tried several OK 049s, the 074, and the 09 back when Herkimer used to run their back page ad every month on Air Trails (mid-1950's).
However, some people had better luck -- Larry claimed to do so, and so did Currell Patty (hmmm? has Currell ever put in an appearance here?)