Dear friend, there are a few observations:
1) DHD-HWH ACDD was a dud, DHN-BSP is likely to be worse.
2) Longer Chair car journeys especially on DD coach are not comfortable.
3) Two rakes shall be required which is undesirable
4)...
more... Better option could be a SF train with chair car accomodation (few Sleeper/AC3 coaches desirable) DHN-Asansol-Burnpur-Adra-Purulia-Rourkela-Bilaspur-Durg-Nagpur leaving DHN at 6:00 AM and arriving NGP at about 22:00.
5) above train if overnight would be even better departing DHN late in the evening