Thanks to Sayam and his dad for digging out an old book and sending it across in reply to the RFC call for bug 247233.
As per an extract from this document, the symbol looks best to be positioned as below:
The above reference is from the book titled Bangiya Shabdakosh by Haricharan Bandopadhyay published by the Shahitya Akademi. Right now Sayam is gathering a copy of the complete three volume set in Kolkata.
