Hey.

Admission is done in AIIMS through it's self conducted entrance test for AIIMS. It is not done through your NEET score/ ranks. Neither does it affect your chance of taking the AIImS entrance. Hence for admission in AIIMS you will have to attempt a separate entrance test and your admission will be done on the basis of your score and rank in that and not through NEET.

Also, to be eligible to take the AIIMS entrance you'd require an aggregate of atleast 50% marks in your 12th boards of you belong to the SC Category.

Best of luck