International student. Should I retake my exams for University of Oxford?

Hi!
I am an applicant from India. I've studied in the national board of CBSE. However, I got extremely bad food poisoning during my final year exams in 12th grade, because of which my marks dropped significantly, and I ended up with 86.5%, and close to 80% in Math.

This, of course, is really below Oxford standards, and so I decided to take a gap year and complete my admissions requirements by giving the US international requirements (of 3 AP classes including Calculus BC and a SAT score over 1500). I took AP Calculus BC, Statistics and Computer Science A, and believe I have a good chance of getting 5 on all 3. Hence, I believe I would be able to complete the Admissions requirements of Oxford. However, would the low score in my final year harm my application? Should I regive my final year board examination?

(To give an overview of indian education system, we have year 1-12 of study. I would typically submit my Oxford application in October of 2023 and then give my end of the year exams in March 2024. However, I was unsure of international studies and decided to take a gap year and complete my high school)