Hello Kishore,

Yes,you can. 87% is a good score and SASTRA expects the applicants to Get a good score in JEE as well. University may  combine the +2 and Jee score and Mark a ranking for all applicants ,based on that they ll call for councelling and still there is a possibility you can get placed in Third round ,which is an open counceling (last year open councelling wasn't there). My friend got placed with 87.25% and 20 JEE in open councelling two years ago. my intuition says there is more possibility for you.but im not sure whether main streams like Mech,CSC,ECE,EEE will be available if you have moved for open counselling,that ll be filled with first two counsellings...Finally yes,you can get a seat.

All the Best Bro!!