A WebmasterWorld thread has discussion around using the geographic target option in Google Webmasters Tools.
One interesting point brought up by Tedster was that when you use it, reversing it and reversing the effect can take a really long time.
I've heard that once your site is targeted to a specific country it can take a long time to reverse the setting if you decide to. If you are not concerned about any traffic outside India, I'd say give it a try and I'm very interested in an up-to-date report on how things go for you.
Another webmaster said he reversed it and the traffic never went back to normal. He said:
I started seeing some change within 2 weeks after the setting but things never quite returned to 'normal'.
Do you have experience with setting up the geographic target and reversing it? If so, share your story.
Forum discussion at WebmasterWorld.