Another suggestion: try contacting an Indian or British museum and ask for someone in the department that handles Indian history. When I was doing some research on Chinese history I found that much of the best material in the area I was researching had actually been written in English due to the historical British presence in China and the interest of British historians in the region. I imagine you would find a similar situation in India, with much material available in English.
Good luck on your rpg--sounds fun! I am actually doing something similar, which is one reason I follow these threads :-)
I have high hopes for it, and thanks for the link! It's quite nice to be able to work on an entire project on my own and not just a few pages of write-ups.