As you have said that the scores you got on the last few tests were inflated because of the repeat questions,so your average score across the tests comes to approximately 640 (factoring in the initial 580) and 680(excluding the initial 580 and the inflated 750). As you'll see that if you clean up the data properly, the picture becomes clearer.The score you got on the actual GMAT doesn't deviate much from what you scored in practice CATs.
The good news in your case(unlike it was in mine) is that you already have a good hold on Maths, so all you have to do is focus on the Verbal section. You'll have to just increase your Verbal score by another 8 points to touch the 700 mark ,provided you're able to keep your Maths score constant at 49. I don't think that improving 8 points looks an insurmountable task. I improved by around 14 points ,though it was over a long period of time and you may not have the patience to wait for that long.
It'd be better if you can provide more details about your strategy for tackling each of three areas on the Verbal section ? How comfortable were you with RC ? How easily could you spot errors in sentence correction questions ? How good your concepts in SC ? Did you practice enough of RC ? Could you identify the problem type in which a particular CR problem would be categorized into and did you know how to tackle each problem type ? The answers to all these questions will probably help is in finding out the root cause of the problem ,so that you don't end up making the same mistake again in your reattempt (like I did )

Great stuff, eternal_optimist (and just fitting that someone with your handle would be the first to jump into a thread like this!).

Adding to what you said, I'd add some optimism to this, too - the fact that your score is already at 640 is a big step, as you're not only most of the way to where you want to be, but now you have a pretty good understanding of where you need to improve. The next few steps should take that even further - be analytical about what you're missing when you do miss questions. As you analyze old practice test results, try to find common patterns in those that you missed. Look at the question type and the REASON that you missed it. You'll probably find recurring reasons, such as:

-Misidentifying the conclusion of a CR Strengthen/Weaken question
-Misreading the question stem of an RC question
-Failing to note a major-category SC error and guessing as to an idiom to make your final decision

Hold yourself accountable for the reasons that you're getting those questions wrong, and then you'll be better able to avoid them on test day because you'll know which errors are likely to hold you back. The good news is that you're almost there - fix that last few percent and you should do well!