Honestly, the only problem I see with your items...

The case looks ok but it's going to be really cramped and you're most likely going to have to remove the driver cage to fit the gtx 1080. I would recommend getting a better case, especially if money isn't an issue.

The drives are fine, WD makes good, reliable products IMO and if you trust them, do it. You won't experience much difference with better SSD or HDD, only slightly faster load times, boots, etc.

I would still get the i7-8700k over the i7-8700. It already comes with a faster clock speed even without overclocking and it still gives you the option of overclocking with your water cooler if you want to get a little bit more performance. The motherboard might even have an easy "overclock" function.

Also, change the power supply, the one thing you do not want is a "cheap power supply" that can fry your whole system as in, one that's not even rated. EVGA makes great power supplies for cheap. For example, the one TriQ has listed in his link;
https://pcpartpicker.com/product/y88...ly-220-g3-0650

Perfectly good, and low priced power supply.