The GTX560 cards arent that massive compared to say a 4870X2.
The 902 is a gaming case. It is quite wide and will fit most aftermarket coolers.
I have a HAF 932, and it really is huge. Wide enough for any cooler. But it's really tall, and has 6x 5 1/4" drive bays at the top (!). If you dont need such a tall case, look at the HAF 912. Its just the same, only shorter.
The Antec 902 will surely fit 2 dual slot GPUs of considerable length, and a large cooler. So dont worry! Buy it!! Good luck with build