Alright I haven't really seen the original question answered very well so I thought I would voice my thoughts.
Personally, I am a WCing person. I love it and will probably never go back to air cooling. That said air cooling is probably the best option for you. Your OC goal isn't very ambitious so air should get you there no problem. I mean the stock cooling might even be good enough. That said I have no idea how you could possibly get to 3.3ghz and be satisfied knowing that you could get more out of it. OCing is like gambling, you just gotta keep going until you finally ruin everything. Also, I have seen tri-sli GTX280 a couple times air cooled and they didn't blow up. They will run hot and probably not have much OC head room, but they won't blow up.
Now, I have a case that is actually slightly bigger than that one and only 1 gpu with no nb or sb blocks and less rads than you will need and I have a hard time fitting everything in. If you want to have your rads internally and cool everything you will not have room for everything as you will need about 3 120.3 rads and either 2 pumps or one large one. The cost alone for the WCing will be enough for another gaming comp. Also, you will have to mod your case. If you want, what you can do is build an external housing for the WCing equipment and just have tubing going from the external housing to the inside of the case. If you must have everything mounted internally than you can get a
MM case as those are made for WCing.