Hey man--happy to offer up some thoughts. Right off the top of my head my friend, YES you will want to retake the GMAT. You are targeting some great schools, which is a good thing. You SHOULD target these places, especially in today's job market (especially given how hard it is for internationals to get jobs). But you need to be more realistic. A 660? From an Indian male...at HBS? : ) It isnt gonna happen brother. You gotta juice that verbal score for sure. Duke and Darden are stretches too man.
Assuming you ROCK your essays, which you will have to, you will still need to show that your verbal scores are up to par. Otherwise, schools will assume that youll have trouble with reading assignments, talking in class, etc.
So. That would be my main strategy my friend. Be realistic--retake that gosh darn test.
And your dreams can come true dude!
If you like the post, give it a KUDOS!