Insead is one of the very few schools with a stated criteria for IR, so unfortunately, I also suggest a retake. If nothing else, you won't have to wonder if the IR was the reason you didn't get in.
Kellog is also a very competitive school, so you don't want to give them any reason to turn your profile away.
740 is a fantastic score, but the stakes are very high at that level of school
From the Insead website:
What GMAT score do I need to apply?
INSEAD does not have a minimum required GMAT score. Rather than focusing on your overall score, we assess your individual results in the Quantitative, Verbal and IR sections of the exam. We need you to demonstrate your strengths in all of these sections. In order to be competitive, you should aim to achieve a score at or above the 70 - 75 percentile in both the quantitative and verbal sections. For the Integrated Reasoning section, we recommend achieving a score of 6 or above. Please keep in mind, however, that the GMAT is just one of several admission criteria. A high score does not guarantee admission, and a below average score does not eliminate a candidate.