Hello Aspirant,

Out of the two mentioned percentiles, best percentile is 70 percentile for you but you are not going to get any good college with even 70 percentile because with 70 percentile your rank might be somewhere around 306900 - 345000 , you can check out marks Vs ranks Vs Percentile from the link given below :-

https://engineering.careers360.com/articles/jee-main-marks-vs-percentile

Or

You can also use JEE-Main Rank Predictor to predict your rank :-

Now it is recommended that you should prepare for upcoming attempts and make a target of at least 96+ percentile for NITs/IIITs if you belongs to General category. And if you are aiming GFTIs then your percentile should be at least 80+. So as you have mentioned that your chemistry portion is weak so what you can do to improve it is just make out the checklist and enlist down the topics of chemistry that seems difficult to you and then start working on it, go through some video lectures, read about those topics and then solve some questions on it, this will definitely improve your Chemistry portion and for other portions as well, you should start solving previous year question papers and sample papers of JEE-Main to get best practice and don't wait for the announcement of fresh dates of examination, because after that you won't get much time for preparation.

You can also check out the JEE-Main complete learner's solution from the link given below :-

https://learn.careers360.com/engineering/jee-main-preparation-material/

I hope this information helps you.

Good Luck!!