Question about Intel Core i5-8600K

It would work purely from the socket.
From experience with an i7 7700K and a Z170 chip, I can tell you that you have to update your mainboard to at least the 6th generation Skylake. Otherwise, your CPU will not be recognised or will not function as desired. But I can't say whether this would also be the case with your desired i5.
How do you see it with a Z270 chipset motherboard? You would have far fewer problems with such a motherboard.
Correct me if I'm wrong. These are simply empirical values

ps: michiizyset: please inform yourself properly for the ninth time before you spout such rubbish

e.g. something like this

Corsair Obsidian 450D (Midi Tower)

Corsair Crystal 570X RGB (Midi Tower)

NZXT Source 340 Elite (Midi Tower)

With the latter, it would be an advantage if you reversed the airflow. This means that the fresh air is drawn in from the back and the top and sucked out again via the two front ventis.

These are just examples. Of course, I don't want to talk you out of the Spec Alpha. It is also a visually beautiful case. I just wanted to draw your attention to it :) Not that you buy it and then say "Why didn't anyone tell me that" ;)

Thank you for this kind and helpful answer.

Basically yes.
The z170 chip is a little weaker in comparison with a 270 chip, but in my opinion it is not really noticeable.
Keep in mind, however, that you must not save on the other components. It won't do you any good if you have a fast CPU and a suitable motherboard and then install weak RAMs ;)