Lots of unanswered questions. Which race are you prepping for? I generally try to hit 5 or 6 OCR's a year, and each are a little different. What length will it be? That will affect how long you will need to run before hitting obstacles. If it's only a 5K, you'll probably only be running a short distance between obstacles. It seems to me that most people have issues with the upper body type stuff. Monkey bars, rings and rope climbs. If you can, go trail running. It will build your endurance and help with fat loss. Easiest way to increase your upper body strength is by lowering the amount of weight your upper body has to lift.