Getting CS at Bombay, Kanpur, Delhi, Madras etc still requires a rank under 500 or so. Correct me if I am wrong but all the headline grabbing salaries are still restricted to these courses and institutes.
No way rank around 500 gives you CS in those colleges. Mine is 595 and did electrical engineering in Kharagpur. Electrical engineering is after CS and EC. Basically Your rank decides what institute and what branch you will be graduating in. Even though Kharagpur is on par with the institutes you mentioned, people don't prefer it as it's not in a metro City.