BF3 max? you'd be looking at two high end video cards for that..Which would require significant cooling. Which makes me wonder what your graphics setup is.
But lets ignore that for now. It looks like the (one) side fan is a good idea. Multiple side fans not so much. The main blowhole and rear exhaust should definitely stay.
Before doing anything else, make sure you have a monitoring program you can work with. CPU-z is a good one, so is speedfan or coretemp. Most Intel users enjoy coretemp.
Regardless of your joy for monitoring, you WILL have to monitor temps if overclocking and especially if overclocking to the level you're talking about. It looks like you've got a decent cooler.
Nice thing is you've got a fan controller for your case fans. This will help in case thermals become an issue.
Next I would take your current config and note the big numbers, that is CPU temp if given, core temps( more important to me), system temp, and maybe GPU. All those can be viewed in Speedfan. Also notable is v core, and any other relevant voltages.
If it isn't too much of a bother, I'd move the A70 into the top exhaust position and note the temps. If it drops any, keep it there. If you don't care because its too much hassle, then forget about it-its likely to be a difference of about 3C max. That can mean alot though for max overclock...
Then you can begin adding fans to see if there are any benefits to doing so. With the Phantom you currently have 1 120mm in front and one in rear exhaust, yes? and a 200mm blowhole and a 200mm side panel intake. You also have two side intakes blowing directly on your hard drive cages. That's a lot of side intake, but what it does do for you is create a positive pressure system which is good.
By adding another 200mm top fan, you'll be bringing the system closer to a 0 pressure situation.
So your choices to me look like this;
1) you could keep the two 120mm side intakes which in my opinion aren't doing much for you. Then add the other 200mm blowhole and see if there is any benefit. This is the max number of fans, intake = 3X120mm + 1 X 200mm. Exhaust = 1 X 120mm + 2 X 200mm. This is approximately equal CFMs on both ends, which creates a 0 or rather low pressure situation. Think of it as 1 atm (atmosphere).
2) keep the intake fans as they are and forget about adding the second 200mm blowhole, which due to its forward location likely won't benefit you. This creates a positive pressure system. This is good. > 1 atm
3) Remove the two 120mm side fans. keep the 200mm and 120mm exhaust, with the option to add a second 200mm exhaust if it does not harm the airflow. Now you have a negative pressure system, which is good. < 1 atm
BTW, it may be quite a bit more complicated than just changing the multiplier and moving vcore to 1.3V. If that works for 4.5 Ghz, then that's great. But don't count on it.