How much of a benefit from SLI 760

So My buddy is leaving to the Air Force and he's giving me his computer which has an Intel 4770k and a gtx 760. My computer is similar but I have an amd6300 (budget build) and I basically plan on putting my HDD in and my GPU (He has a nice case and obviously his 4770k is better than my 6300). I was wondering what kind of gains I will see with two 760s? Also: His is strange... It has the reference cooler but it is a SC edition and mine has the ACX cooler (I apologize if that's not the cooler, can't 100% remember) and is also super clocked. Are they able to be used in SLI?

Looks like that answered both of my questions. Thank you very much.