Hii,i am here to help you according to your query.To get into NIT:

JEE Mains is considered.

2. Your board percentage should be above 75%.(no advantage of bringing 90%)

In GUJCET board percentile matters as gujcet rank is based on 60% board percentile and 40% gujcet marks.

Hope,this information helpful for you.Goodluck.