I think you're on the margins for INSEAD with your GMAT score -- it's really the only thing holding you back. You still have an outside shot because of your extensive international experience (which INSEAD values much more than any other b-school) so that can certainly help you. However, it would be a sweet spot for you if your score was 700+.
For Oxford or IMD, you should be competitive with the score as is. Again, a 700+ is ideal, but for these schools you should be fine.
Best thing you can do is find a way if you can squeeze 20 to 40+ points on the GMAT.
And of course, doing the best you can on the essays.
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