Here are your odds:
As of 1/13/17
What percent of samples can get an overclock
at a vcore around 1.4v.
They come from silicon lottery which bins chips and sells the better ones for a price premium.
On a given chip, your upper oc limit will be the vcore you can tolerate, not the cooler.
In a well ventilated case a cooler like a Noctua NH-U12s will do the job and keep temperatures reasonable.
On your OC plan to use the AVX offset option to underclock when AVX instructions are present.
Delidding should be done by an expert.
It will reduce temperatures, but I would not bother.
The processor is heat tolerant and will not shut down until about 100c. or so.
Under normal use, you will be much less, I would expect perhaps 75c.