Colleges in Karnataka

Diploma can't get in NIT.

Yes, your rank is good enough to get admission in Manipal University. You can apply for admission.
Good luck.

I got 300-350 in NEET. Will I get admission here?

Use college predictor tool for better results
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor&ved=2ahUKEwjdmKnz4bHiAhU1jOYKHZnJDRsQFjAAegQIAhAB&usg=AOvVaw1N9BzFtyUCP4JU-2UQHQ0H

Bharath College of Science and Management
Khadir Mohideen College
Ponnaiyah Ramajayam Institute of Science and Technology

Hi,
First of all congratulations, with 79.24 percentile in JEE Mains Paper 2 exam and a good score in your class 12th, you can surely secure admission in good colleges across the country. It would have been easier if you could have stated the state/ region, you are seeking to pursue your B.Arch programme. Check the link below to get a list of approved architecture colleges.
https://www.coa.gov.in/index1.php?lang=1&level=0&linkid=25&lid=26.

Hi, yes you can change your college by writing a change of college letter to the university you are currently studying in, from where you need to obtain a NOC and also from the college you are currently studying in, then you need to submit those NOC's along with the admission form to Dayananda Sagar College Of Engineering you are seeking admission.

Hi, you can submit your NATA scorecard along with your 12th scorecard to KEA-CET for admission to KLE Technological University BVB college of Architecture government merit seat. For private management seat you can approach the college directly.

Yes, it's a good score to get admission in Reva University.