Hello aspirant,

According to your question if you get 1000 rank in BITSAT but haven't 75% in PCM aggregate then you are not allowed to take admission in BITS Pillani. According to their eligibility criteria you must have 75% in PCM aggregate and also at least 60% in every subject that is physics, chemistry and mathematics. Also I am giving below link of eligibility criteria of BITS Pillani that will may help you.

https://engineering.careers360.com/articles/bitsat-eligibility-criteria

Best of luck for your career.