First off you should consider overclocking just because there is no harm in it as long as you aren't going for the craziest OC levels and it's extra performance that you paid for so might as well have it right? I've modified your list with my recommendations for saving money in the right places so that you can get a better cooler and still have it cost a little less than your original build and still getting what you want from the other components.
My changes will be explained as follows:
A SATA SSD is perfectly fine. You will not see a performance difference between this one and the M.2 one you originally selected and will cost you half the price therefore I selected it for you.
The PSU is great and all but you can get exactly the same if not maybe better for less thusly I chose the new FOCUS series
I switched up the CPU to an i5 because unless you plan on doing stuff with certain applications that would require an i7's hyperthreading you don't need one.
and of course I gave you a sweet cooler for the CPU so that when you do start overclocking it'll run cool at the higher clock speeds.
And then I chose the motherboard to save you money while making sure that is offered quality construction and a good ability to overclock. of course with the money you've saved you can go for a higher end ASUS board. Honestly when it comes to overclocking I find the ASUS boards to be the most capable.
All in all this is my recommendation for a build with coffee lake. I would say you could actually invest the saved money into a better case (not that the s340 elite is bad but you can get better for sure)
Lastly I would say you could go with a 250GB SSD also since it is unnecessary to have that much SSD storage if you are a gamer. Your OS and all major applications will fit perfectly on the SSD while games can be installed to the HDD. I have a 250GB and I installed a bunch of programs and drivers and even have some files that I save to it and I still have over 150GB of free space so you can save money there as well.
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel - Core i5-8600K 3.6GHz 6-Core Processor ($256.89 @ B&H)
CPU Cooler: NZXT - Kraken X62 Rev 2 98.2 CFM Liquid CPU Cooler ($156.29 @ B&H)
Motherboard: Asus - Prime Z370-P ATX LGA1151 Motherboard ($139.99 @ B&H)
Memory: G.Skill - Ripjaws V Series 16GB (2 x 8GB) DDR4-3000 Memory ($189.99 @ Newegg)
Storage: SanDisk - Ultra II 480GB 2.5" Solid State Drive ($129.99 @ Amazon)
Storage: Seagate - Barracuda 2TB 3.5" 7200RPM Internal Hard Drive ($59.99 @ Amazon)
Case: NZXT - S340 Elite (Black) ATX Mid Tower Case ($89.99 @ B&H)
Power Supply: SeaSonic - FOCUS Plus Gold 650W 80+ Gold Certified Fully-Modular ATX Power Supply ($69.99 @ Newegg)
Total: $1093.12
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-01-31 22:17 EST-0500