invdepth

Don't worry too much about a case being able to hold a GPU, just look at the specs and it'll tell you the GPU lengths it'll accommodate. There is really no need at all to go over the gpu length to get more space at all. For my first build, i went ahead and got a massive case as i thought I'd need it for my GPU..... ended up really regretting having such a huge case... Just warning you! :unsure:  Airflow is something case-wise to maybe worry about more than space, esp with a possible sli deal.
 
Also, definitely try for the 970 if you can, better than 2 960s. It'll last longer, you'll have better upgrade options, and the 4GB on the 960 isn't incredibly useful. 960 just isn't powerful enough for it to be awesome. (unless for Skyrim+lots of texture mods?)

CPU: If you are getting a Z97 board, you may want a "k" series processor, that is unlocked to allow for overclocking otherwise:
MoBo: If you do not plan on overclocking, and dont want a K cpu, get an H97 motherboard, as it will be cheaper and you can use money on:
GPU: I personally would reccomend upgrading to a 970 if the cost works for you. 2x 960 will probably still struggle a bit at 4K. 
 
Edit: It WILL Struggle at 4k. 
http://www.guru3d.com/articles_pages/asus_geforce_gtx_960_strix_2_way_sli_review,16.html
 
2x GPU next to eachother is fine, as long as you have proper case airflow. 

Looks like a great setup, you shouldn't need to worry about SLI, the 960 doesn't output too much heat. 10/10 would spend 원 again