You have scored very well in JEE MAINS but unfortunately for you, IITs consider only JEE ADVANCE marks for admission. If you have scored well in JEE advanced too the well and good, but without that, I can not really tell you if it is possible. But you can definitely get admission in NITs and IIITs with your excellent rank in JEE Mains. You can apply for these institues through JoSAA, and that can be done through the JEE mains website. NITs and IIIts are also government colleges and esteemed colleges. So if you get any of these don't leave the chance. You can get the list of Top NITs and IIITs, and you can prioritise between them considering all the things that you want in your college, including Branch and Fee Structure. These being government aided colleges don't have fees as high as that of private colleges. As you prioritise and enter the list in the JoSAA rounds, it automatically checks your rank and marks with the cutoff, and allot the college and course nearest to the top of your list. All the Best. Hope you get the college and stream that you want.