287 is not a promising score even if a person belong ST category, especially if you're aiming to take admission in any government college. Because if you see the previous selection criteria I'd say 450-480 would be the safest to ensure a seat for a ST candidate.

Yet I'd suggest you to apply for counselling and look out for private colleges , if you can afford.

Hey !

With 287 score in NEET UG ,and being an ST candidate , your son have chances of getting a seat in private medical colleges only. He has no chances for a govt. MBBS seat. Since , you haven't mentioned your quota and region , i can not tell you the name of private medical colleges where your son can get  a seat.

To predict his chances of getting a medical seat on the basis of NEET AIR ,USE NEET PREDICTOR TOOL 2019:

https://medicine.careers360.com/neet-college-predictor?icn=NEET_clgpd&ici=sticky-qna-wap