The only original set of rules dedicated to your period is "John Company: The Conquest of India, 1750-1860."
Rather than take my decidedly biased word for it, you may wish to follow this link to a review here at TMP of the First Edition. TMP link
You may find additional information and comment by running a search for "John Company" through the 19th Century Boards here at TMP.
Currently in their third edition, JC may be read about and even ordered (in Print and PDF Editions) via this link
Of special note is that the rules may be played with ANY scale miniatures as casualties are figured by the BASE, not the FIGURE. Ground scales, ranges, etc, are fixed, not needing any adjustment.
I can send you more information of the basing system simply by PM'ing me, if you like.
It took over 8 years to research these rules with the help of others from around the world--including India, of course--to complete what we wanted other gamers to be able to experience!
Cheers!
TVAG