If you want AMD cards you could get something like this http://uk.pcpartpicker.com/p/2heGj, if you need more storage you could grab another 3TB drive.
Or if Nvidia is your thing you could get this http://uk.pcpartpicker.com/p/2heV7, and you would have enough for another 1TB drive i think if you wanted.
You could save money and get a smaller ssd, but i figured you probably have a bunch of games and applications, you could get like a 120GB ssd and only put your OS and a few games on it and then spend the rest on more hard drive storage and or maybe up your graphics cards a bit more and grab this
http://uk.pcpartpicker.com/p/2hfhm but you do lose quite a bit of storage, going Nvidia is probably your best bet, as i hear sli is smoother than crossfire.
So how I see it you could go for AMD if you want more storage and good performance, and go with Nvidia gtx 770 sli if you want a better experience but less storage.