Hey C Bear. I'll give you some recommendations from first hand experience and product knowledge.
So, your CPU is a pretty solid choice. I wouldn't worry about it bottlenecking your GPU too much, especially as you currently have a 750ti. What I would recommend to you, if it's in your price range is the single best GPU you can afford. If you're happy to buy a 1070, I would hop on it. It will pair well with your CPU and you'll only see bottlenecks from an outdated CPU if you're playing big open world games; Cities Skylines, MMOs, RTS games, etc. Now, moving to a 6600k or 7600k isn't going to give you huge improvements, unless you plan to overclock (I will assume you do plan to OC because you picked the 7600K; more on this in a bit).
If you don't feel like buying the best GPU you can because you have money now, the gtx 1060 and rx 480 are both very good cards. I would buy the one that fits the games you play (if it takes advantage of Vulkan). Since both AMD and Nvidia's newest series support DX12, that isn't going to push AMD "ahead" anymore. I wouldn't recommend the 8GB 480 or 6GB 1060, they just don't really make sense. Based on your resolution and games you play (please look up specific benchmarks for those games as I don't know what games you play), I would recommend @1080p you get the GTX 1060 3GB. If you want to play at 1440p, grabbing the 1070 would be your best option but you could also grab the 4gb rx 480 if you want to save some money.
For a better understanding, I recommend the 3GB 1060 because it is significantly less than the 6GB version, and also has 10% less cuda codes (this does not mean exactly 10% less FPS). The RX 480, however, does not have this disparity between the 4GB and 8GB versions. At 1080p you won't be pushing 4GB of VRAM (in gaming). At 1440p, however, you may. This is why I would recommend the 1070. The RX 480 will still play 1440p happily and you'll only notice VRAM capping in heavily modded games like Skyrim or possibly Shadows of Mordor. Most games aren't going to cap you.
If you play GTA V you will notice how it tries to stop you from going above your VRAM. My GTX 770 is a 2GB card and I currently have my settings "using" almost 2500MB of VRAM. I have yet to experience a crash or stuttering (which would be VERY noticeable if you capped your VRAM).
Long story short, I don't want to see you waste money. I would recommend a GPU upgrade at this time and maybe a CPU upgrade one or two generations from now. Edit: Your RAM is fine though another 8GB wouldn't hurt WHEN you upgrade to DDR4. I wouldn't bother with it now unless you need it for productivity, not gaming.