Hi, I'm new.
Should be more than enough. I’m rocking a 560 series and don’t have a problem. Framerates only dip if there is a truly crapton of stuff on the screen. That said, I wouldn’t mind SLI.
Make sure that you have a strong power supply so that the hardware can work to its fullest capacity. Also make sure it has good cooling so that the heat can stay under control. The specs you are quoting are fine though.