Not sure why a different card in a different case really has any bearing on your question.
I did not actually install the card in my Scout case, but had a 6970 card in hand (same size as the 6950) to see if it would fit. It looked like I could get it in if I took maybe a quarter inch notch out of one side of the hard drive cage.
You might also be able to stick the back end of the card inside the cage and angle it into the PCIe slot, which would obviously be the first approach to take.
What is the maximum length graphics card supported?
The CM Storm Scout is designed with portability in mind. It can accommodate the largest 280GTX or HD 4870 X2 type cards. This includes all GPU 10.5" or 267mm in length or shorter. GPU cards have a maximum clearance for 10.6" or 270mm maximum length inside the Scout.