With the OS 120 you will want a plane that isn't any more than 9lbs. There are some very good selections: The new Funtana looks like a winner to me. Also the H9 Frenzy looks like a lot of fun. The old standby UCD would be excellent with this motor (my favorite all time plane), if you want a profile, the OMP Fusion is a good plane for that engine, just to name a few.
Have fun.
Thanks
Barry