I am engaged in a project that will draw on a few proper nouns from nineteenth century India, many of which are Bengali. Is there a transliteration standard used in modern published works for older Indic proper nouns, particularly those that exist in print in "unusual" forms?  In other words, does one follow the "old" Bengali spellings, or revise them to follow Sanskritized versions?

Thus, e.g., Keshub Chandra Sen, or, Keshub Chunder Sen? 

Also, are diacriticals used for proper nouns? Vivekananda, or, Vivekānanda?

And, again, are diacriticals used for organizations? Arya Samaj or Ārya Samāj

For all other Sanskrit elements, the project does use diacriticals (e.g., Purāṇa)

Any guidance is appreciated!

Herman