The Hyper 212 is a good HSF and the TX-3 is good TIG. No one is going to be able to guarantee that you will hit 4.0ghz though.
OCing goes chip by chip. You can have two identical CPU's side by same both using the same cooling solution and one may OC further than the other.
So again, good heat sink, good thermal grease, but asking if a particular chip will reach a certain clock speed is somewhat out of the question.
Hopefully someone with more specific E6300 experience will post, but I believe 4.0ghz on that chip is a little ambitious.