It's hard to say exactly what your temperatures will be as they will differ between different examples of the same chip - you may have a hot one, or you may have a really good one that runs really cool even when heavily overclocked.
My advice with a 4670K would be to get the bet cooler you can afford, as you don't want your cooling solution holding back your overclock.
That said the H100i is a really good cooler - there are few better, you should be fine with it, and I would expect it to easily keep your chip under 70degreesC even under load overclocked - that's what it is designed to do after all (and all provided you have it set up in a case with a sensible airflow)