82C is no problem - GK104 is built to run at that temp. It may be noisier than you're comfortable with, but it will also exhaust all hot air out the back of your case, which will keep your other components cooler.
Any GTX 760 is the better choice if you're downgrading from a 680. For one reason - memory bus width. Dropping from 256-bit to 192-bit will be a jarring experience, especially if you like to run with multisampling. Also, the 660ti can only reliably use 1.5GB of its VRAM because of the bus-width/VRAM mismatch. Trust me, going over 1536MB in a game is not pretty.