From that picture, you look like you will be ok. There is more than enough room. However, Heat may be an issue. I wont tell you yes or no on whether the setup will be ideal with temps, but i think there is ample room to "fit" them in there. Do some research, as a pci-e fan for the gpu might be a great idea...if it will fit with both cards. I think it will. Would be a smart investment if worried about the post in your OP. I would recommend these pci-e fans:
you have lots of room, there are 2 slots in between your 2 cards so there is a whole slot space in between,, typically there is not much you can do about the heat as it will get hotter in the case from more GPUs, but this is best case scenario with the extra spacing.
You will just want to manage airflow in your case,, personally I like the Antec Tri Cool fans and run them on low as you can barely even hear them run, if you need your case to be cooler, just turn them up to medium but you will start to hear them for sure.
Make sure you get an overall flow front to back of case -- I also like to remove the PCI slot cover below the graphics cards as well to help with air escaping case,, I know they are there to help on keeping dust out,, but I never really notice a difference with them on or off,, case gets just as dusty.
if you only buy 1 fan, place it at the back of your case if you have air vents on the side of your case(i find the side vent makes the air escape the case prematurely if you put the fan on the front),, if you dont have air vents on the sides, put your 1 fan on the front lower level of case.
if you buy 2 fans, put one up front and one in the back.