Here's the Links page for Bengali, Hindu Castes and Names. http://www.purespeed.com/personal/mazumdar/bengname-hinducaste.html
My greatgreatgrandfather Alfred Busby (sp) was said to be a Burmese Bengali immigrant via Calcutta. The British also used Bengali contract labor early in the colonization of Burma and some descendants were contracted again elsewhere. The name Busby was probably taken on conversion. I wish I knew what it had been.