There is no problem with LENGTH AFAIK.
The case states "314mm" (12.4") but there's at least another inch, possibly 14". I believe that's for the 6-pin/8-pin cards that may have power on the end. The card he mentioned is 274mm, though there are three cards in that category (probably the same length, plus he'd probably KNOW if was too long).
*I had the SAME PROBLEM on a previous case. It was difficult to fit the end of the card into the proper groove between the end of the case and the motherboard.
I turned the case on its SIDE, then used a flashlight to see where it should fit, and eventually got the card to fit.
**Once your card is seated, don't forget to push the plastic lever that locks it in place before removal or you'll break it (on the motherboard).
Also, I couldn't tell from the pictures if that card has a backplate or not, but if not I suggest you rig up something similar to a chair leg that takes a little pressure off the motherboard (between case bottom and card, as close to the end of the card as possible). The card should be almost LEVEL. Reducing flex also avoids the eventual card failure that can arise. It's fairly common.