IIT Kharagpur - Indian Institute of Technology

You should have a rank around 1500 so that you can securely get aerospace engineering. Also, alternatively you can take any of the branches being given to you now and then after 1st year can change the branch on the basis of your performance in 1st year because 1st year subjects are common for all.

It seems really difficult to me that you can get aeroscope engineering with the percentile you have got.

Eligibility criteria for M.Tech Naval Architecture is:
Bachelor's degree in Naval Architecture/ Marine Engineering/ Nautical Science/ Ship Building/ Mechanical Engineering/ Civil Engineering/ B.Arch or the equivalent.

Taking admission in M.Tech after clearing GATE is easy, and the GATE Score requirement generally depend on your category. If you are talking about general category, the GATE score should be above 55.