Thanjavur

Yes, you can get a seat at Sastra University. Your marks are really good enough to get a seat. You should apply under stream 1 as you have appeared for JEE Mains exam.

SASTRA University MBA admission is based on a national-level entrance exams followed by a Personal Interview (PI) conducted by the university. In order to be eligible for this programme, students must have completed their Class 12 and undergraduate degree in the relevant stream. The entrance exams considered for admission, include CAT, XAT, AIMAT, CMAT and AIMCAT. Those with a valid score in one of the afore-mentioned exams are eligible. However, the final eligibility for admission to MBA at SASTRA University varies depending on the entrance exam that the student has taken. Read more about MBA admission at SASTRA here. 

To get CSE at SASTRA Deemed to be University in Thanjavur, your rank in stream 1 or 2 must be less than 500. The cut-off rank varies from year to year, however you should have a rank of less than 500 to be sure of getting CSE at SASTRA Deemed to be University. Unfortunately, with a state rank of 690 in Stream 1 and 112 in Stream 2, it appears that you will be unable to enrol at SASTRA Deemed to be University for CSE or IT because places fill up below 1000 rankings for these courses. I hope this was helpful.