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. Your merit according to what you've written in the question is 77.5 and you have a good chance of getting admission, on basis of number of seats available.

Here's more about your college preference:

https://www.careers360.com/colleges/government-engineering-college-thrissur/barch-course

Good luck!