Very simple route and convenient time for you.
Punjab mail 12137 at nasik rd at 23.25 reach itarsi
by 7.40(8hours 15 mins) and from Itarsi take either Tamilnadu Exp 12622
at 9.53 reach chennai at 7.10(21 Hours 17 Mins) or GT exp 12616 at 7.35(if suppose it comes 5 min late on your day) reach chennai at 6.15.(22 hours 40 mins)
Any...
more... way you need to spend 30 to 31 hours on any route(either NK-KYN-PUNE-WADI-GTL-RU-AJJ-MAS or NK-ET-MAS). So i am sugessting a route with minimal change of trains and as per your convenience to reach chennai at early morning.