Creating this list based on a discussion on a Film Companion facebook group to keep track of them. Some really good movies came up. A lot of them are critically acclaimed and some went unnoticed.
I have created a separate list for all movies before the year 2000 here https://www.mymovierack.com/list/classic-old-less-known-bollywood-gems-ongoing-list-lys20tm
Please feel free to suggest more.