HI there,
Hope you are doing well.
As per previous statistics, with 55 marks in JEE Advanced, you can get around 700 ST Category rank.
With this rank, the possible branches for you would be:-

• IIT Goa:- EE
• IIT ISM Dhanbad:- EIE
• IIT Palakkad/ IIT Bhilai:- Mechanical
• IIT Kharagpur:- Agriculture Engineering

And with 1000 ST Rank in JEE Mains, the possible branches for you would be:-

• NIT Jalandhar:- CSE
• MNNIT Allahabad:- IT
• NIT Kurukshetra:- Civil, Mechanical
• NIT Rourkela:- EIE
• NIT Warangal:- BioTech

I think that you should go with the NIT Branches as they would get you better placement.
Hope it would help
Thank You

Hello Shubham!

In JEE ADVANCED it is not wise to decide your chances of getting a college by roughly predicting through marks. The cutoff varies highly depending upon various factors. Sometimes even a 60 marks scorer of ST is disqualified or sometimes even a 40 marks scorer qualfies.

It's better to use Careers360 tools in such case as they give you some good predictions.

https://www.quora.com/profile/Santwana-J-Singh

You can check out this college predictor for a clearer idea. 

Hope that helps!