That will work but I recommend buying a non-referenced graphics card like
this one. It features an awesome ACX cooler for better cooling and performance. In terms of SLI, the best configuration for the two cards would be put the ACX one on the bottom, and the referenced card on top. This allows the ACX cooler access to cool air. If you put the ACX one on top and referenced on on bottom, the ACX cooler will be pulling in warm or hot air from the bottom card, making it less efficient. The referenced card uses a blower-type cooler so it'll be fine where it is.