Hi Rohit,
In JEE Mains paper 2, a rank below 500 can ensure you a seat in Manipal, as this is one among the first prefered colleges. For a rank below 500, you should aim for a score of 320 and above, as the competition is tough every year. As you are from the home state you can aim for a rank below 800 to be safe.
All The Best
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