finance question

In a strictly educational capacity, if the projected and required return are the same, then you accept the project. That is to say you accept projects with an NPV of Zero or greater.

In the real world, things get much more complicated. You might reject a project with a much higher IRR than required because of external factors that can't be done in the straight analysis, because your boss is in a bad mood, or you just got stung on something else that sounds similar.

I don't think Exxon would move too aggressively in pursuit of a 5 barrel per year production site, regardless of whether the project had a positive NPV and 400%+ IRR.

Not sure about the size issue for an academic question (which is what I think OP is asking). If you can make a case that some of the assumptions may be a little too optimistic/pessimistic that can help push your decision one way or the other ("technically the NPV is 0 at the given lending rate but our associate is sleeping with an MD in the sponsors group so we may be able to get lower interest rates, so I would do it.")

From a purely academic perspective, I believe an NPV of zero would actually make you indifferent as to whether or not to go forward with a given project / investment.

With an NPV of zero, your IRR will be identical to your cost of capital.