It is not the font which is to be converted, but encoding.
Your file uses - likely - an ISCII encoding. Those ISCII encodings are 8bit encodings, and they were made such that when shwoing the contents with a different Indian alphabet ("font"), someone knowing that alphabet could still read the contents. Such behavior may cause confusion. Let me tell you again: it is the encoding which needs to be changed, not the font!
See also http://en.wikipedia.org/wiki/Indian_Script_Code_for_Information_Interchange