Hello!
Your admission through NATA is based on your merit system. Divide the NATA score by 4, and your CBSE result by 2, and add them to find your merit out of 100. Normally colleges accept a student who has 60+ merit overall, and sometimes colleges even go for lower merit. But JJ college of Architecture is very hard to get into, and you need atleast an aggregate of 150+ for your admissions.

Here's a list of other colleges that accept NATA score:

https://engineering.careers360.com/colleges/ranking/2018/top-engineering-colleges-in-India-accepting-nata-score?page=1

Good luck!