Hi Sajith, 

congragulations! Its a pretty amazing score you have scored.But it will not be possible to admit yourself into any of the goverment colleges in Tamil Nadu using your mains score ,because the goverment college seats are filled via a counselling process called the TANCET based solely on the 12 th passing marks of the students ,according to which they will be given a cutoff , based on which they are ranked and given a set of colleges among which they can select the desired ones.

You may try applying for TANCET,if you have become late, or if the last date for application has been passed away already ,then I would suggest you approach any of the affiliated private college to enroll via management quota or else there is a college in chennai called SASTRA,which supposedly might have branches in other parts of Tamil Nadu too,which selects students based on their merit considering their JEE mains marks too.

So,Please try SASTRA which is one of the best colleges available in chennai and TamilNAdu itself.

Hope it helps.

Good Luck!!