A Merit score around 150 or above will get you into Sir JJ College of Architecture.

In your case, you have 103 in NATA and 90% in 12th Boards. Which gives you a Merit score of 141.5 (i.e. 51.5 in NATA + 90)

Now if you want, you can take a risk and go ahead with this score or work hard and give NATA again as you can attempt NATA five times and your highest score is considered out of all the attempts that you make.

Hupr you understand and good luck!