gpuboss is not the best site for comparisons. It's decent to get some straight comparisons on specs but that's about it. There are not a lot of good benchmarks out there for the 960 yet because it's still pretty new and I think the benchmark sites are waiting on more stuff to release so they can release better comparisons. Since the 960 performs very similarly to the 770 I have been using it's benchmarks for a point of reference:
http://www.anandtech.com/bench/product/1037?vs=1043
Also, I don't see it being $60 more. The cheapest 270x's are around $160 but ones with good aftermarket coolers(which you really need on R9s 2xx's) are closer to $180. Meanwhile, you can still get a good 960 for $200-$210. I'd get a 960 as it not only performs better it does it while using far less power and therefore running cooler.
That said, your PC is fine. Why wouldn't you just OC your 2500K. The 4690K is not going to perform a lot better then the 2500K. It will be very little increase in performance for the amount you are going to spend. Get a top of the line aftermarket cooler like the Noctua NH=D15 and OC your 2500K and you'll be within 10% od what a 4690K can do and will likely be performing better than a stock-clocked 4690. Spend the money on a GTX980 instead.