Let me make a (strong) suggestion that you broaden your search to include some schools down to perhaps the 50th ranked university. Don't neglect the ivies, but Stony Brook as a "safety school" is probably too ambitious if you don't want to be utterly disappointed.
Let the school you apply to do the conversion and don't worry about it. It is what it is. Your guess or computation of an equivalent is immaterial to any decision.
Note three things. First, is that your more recent grades are more likely to be considered as indicators than earlier ones.
Second, people realize that the grading itself in Indian universities is quite different than in the US. Here, top marks are pretty common. In India, it is, IIRC, much more uncommon.
But third, and most important, your admission will be based on broad analysis of your likelihood of success, not narrow, single numbers like GPA. In particular, letters of recommendation are very important, more so than some other places. And write a good "future focused" SoP, detailing what you can about your plans for study and thereafter. Don't use it to recapitulate what is already in the CV or try to make excuses for any shortcomings.
Yes, you have a shot, but the competition is fierce at the top schools. Put together a complete application package that indicates future success. Don't worry about what you can't control.
But cast a wide net, not only top of the top schools. If you cast a narrow net, then rejection by one will likely result in similar outcome at others. All of the US R1 universities are more than merely competent in most fields. And your eventual advisor will have a bigger impact than the overall reputation of the universities. Good advisors can be found lots of places.
To somewhat answer the topline question you posed, you are probably fine. But the difference in educational systems means that everyone who does a conversion will likely come up with a different number. Even in the US, 3.5 at one place means something different at another.
At some universities in the US, a student who did 90/100 on everything, could actually have a 4.0 GPA. At others, it might be a 3.7 or so.