Presumably, this is for gaming.
A rule of thumb is to budget about 2x the cost of the processor for the graphics card.
For your purposes, you could look at a less expensive I5-9600K. 6 cores is plenty for gaming.
Regardless, I think a i7-9700K is about the same price as a 8700K and will outperform it despite having 8 cores vs. 12 threads.
The 9th gen processors have soldered heat spreaders so they run cooler and will OC better.
For any K suffix processor, you need a good cooler. Noctua is excellent quality, but a downdraft cooler is not very efficient.
The NH-L91 is totally inadequate.
The noctua NH-D15s is as good as it gets.
I think I would defer on the HDD until you actually need the space.
Start with a 500gb Samsung EVO either 2.5" or M.2
That's a low profile cooler. It's meant for narrow home theater style cases and other small form factor setups where bigger just isn't an option. Noctua does not recommend using it if you intend to overclock.