I got 74.77% in Maharashtra board.OBC.math76 chem57 eng75 phy-67 electronics161/200 environment 50/50 .so am I in top 20 percentile for NIT
Minimum 355 marks in OBC category was cutoff for 2018 Maharashtra board top20 percentile.
Since your aggregate is above 355marks then you are surely eligible.
https://engineering.careers360.com/articles/top-20-percentile-of-class-12-boards-for-nits-iiits-and-cftis