When running SLI quality matters as much as quantity. Pretty much any EVGA Super Flower Leadex unit you can buy (B2/G2/P2/T2) are among the best of the best. It should handle it fine, you might want to go with the 850W G2 to be on the safe side.
As an owner of 2 4Gb 770s in SLI I wouldn't run them on 750w PSU. While it may work it going to get very close to maxing the PSU. If you have a FX-9xxx sereis or heavily oc'd 8xxx series cpu then you'll definitely need a bigger PSU.
When running SLI quality matters as much as quantity. Pretty much any EVGA Super Flower Leadex unit you can buy (B2/G2/P2/T2) are among the best of the best. It should handle it fine, you might want to go with the 850W G2 to be on the safe side.