hi i have been wondering about the same question regarding arbitrage. i plan to do the same.
in my view, the hurdle you will face is how to transfer the money from India to abroad.
you can easily buy btc overseas and transfer to your Indian wallet (unocoin, coinsecure, etc), and then sell on indian exchange. then you will request withdrawal from the exchange, which can take 2-3 days as i understand. this is where it gets risky - withdrawal happens to your indian bank account (and here is where indian authorities can question the sudden influx of funds into an a/c).
in light of the current absence of regulations, you may do so at your own risk. i plan to do so in small quantities to test the waters.
Remember the 2013 case of Ahmedabad where ED raided a bitcoin seller as he had violated FEMA? I think its more about FEMA rather than the sudden influx of funds into your account. I asked my CA but he has no idea about it. I think consulting an advocate before getting into it would be right.