Well, you are right. The Lightning series is perfect for overclock, but in the rig that you want built and the use that you want the Gaming series is more that enough. Why? Because the Lightnings are excellent for overclock under extreme conditions (liquid nitrogen more specifically) but on air you can get similar results with the gaming model.
Not all GPUs can be overclock at the same level, not all components show the same results with overclock, eve, with same model and bought in the same store you will get different results.
In this case, for your needs I recommend you this:
Get the Gaming series that is enough for your needs and try to move on to a better motherboard (G65 gaming or Z87 MPower) since that CPU also needs a very good motherboard for an stable overclock.
Just my 2 cents.