well the 680m has 1344 shader cores @ 720mhz where the 770m has only 960 shader cores albeit clocked to 811mhz. I personally don't think it is possible to match the performance through a clock bump alone. You would have to make up for too much core count deficit. Also the memory pipeline on the 680m is 256-bit wide vs 192-bit on the 770m. That means the memory bandwidth is far lower too.
So, no sorry. I don't think you will quite push it there, not without Ln2 (liquid nitrogen) anyway.