yes...(but you have NO room to maneuver in the sense of overclocking...)
NO... the gtx780ti is between 260 - 328,
http://www.techpowerup.com/reviews/ASUS/GTX_780_Ti_Direct_Cu_II_OC/22.html
and an overclocked 4770k is using about 120 watts so it is really about 500 max.
the maximum power draw of your system should be less than the max rating of your PSU.
so you will be fine if you only OC your 4770k on stock volts, with a 780ti... 40 watts idle + 89 cpu + 328GPU (max) is 458... you might be "breaking bad" depending on the model of gtx780ti though.
but beware of the "
dark desire to overclock" lol when you use a power supply at its limits...
(BTW, "litecoin mining on your GPU is the same power draw as running FURMARK... and the gpu makers called furmark a power virus!... i wonder what AMD thinks about litecoin mining, since they have jacked up the graphics cards price 50% from the "release" pricing (look at techpowerups "listed pricing" in reviews of amd cards and compare to newegg's prices)