A few days ago I had posted some of the details of the stations which existed in 1868. This appeared in the annual report of 1868-69.
The entire railway network of that time is given in these 9 pages. It also includes places which are now in Pakistan and Bangladesh. Have fun in comparing the old station names with the present.
This and other annual reports, besides other rail-related documents, can be accessed and downloaded from https://dspace.gipe.ac.in/xmlui/handle/10973/17705 and by using the keywords (India, railway).
A smaller number of annual reports are on archive.org, which can similarly be accessed and downloaded.