The Hyper 212 Evo is fine for the 2600K. Sandy Bridge chips run quite cool and you will probably hit max voltage before temps become a problem. Keep your chip at 1.4v max, better is 1.35v or below if you want your CPU to last. I run at 4.5Ghz and 1.32v with Hyperthreading on and my temp are low 30s at idle and high 60s running Prime 95. Everyday temps do not go over the high 50s. I have a Scythe Mugen 2 Rev B. They replaced it with the Mugen 3 now though. I use IC Diamond thermal paste.
Any advice for the overclock?
Where can I go to obtain some basic settings to try that are known to work and run stable ?