Hi Filipmunk,
In theory, to dissipate 100W, you need 120mm of rad.
Here you have 240mm so you can dissipate up to 200w staying in "normal" temps.
The 8600k eats about 180W maximum during extreme overclocking.
So IMO, you're good with that cooler correctly configured.
After that, it depends on the tim between the die and IHS.
But, as always, the experiment will give the results.