Many important facts are missing from your description but I am confident that we can already conclude that it would almost certainly be impossible, for two reasons:
- For you to be French, your father would need to have been French when you were born. From your question, it seems he was born before your grandfather became French. Theoretically it could be possible that your father became French at the same time as your grandfather but there are several conditions and you would need documentary evidence of that (for example a décret de naturalisation naming your father).
- Even if your father was born French he needs to make use of his citizenship (that's called possession d'état and means something like applying for a passport) lest his citizenship lapses and it becomes impossible to transmit it to his children. We have a bunch of questions about this already but 1936 is a long time ago and it's very likely this rule would prevent you from claiming French citizenship, even if your father was, in fact, a French citizen.
Both are major hurdles in themselves and that's ignoring any complication arising from the handover of the French territories in India or any potential change in the rules over time.
Either way, without evidence that your father was French and making use of his citizenship, there is no way for you to prove you are French yourself. From that perspective, your grandfather's status doesn't matter much.