Not easy.
Your proposed timings for TDD-RJY are too aggressive. KVR-RJY section alone needs almost 15 minutes on most days and many trains get held up at RJY outer. TDD-RJY in 28 minutes, is not possible everyday. At least 45 minutes, is a reasonably achievable time.
Also, CCT has no water filling or train cleaning facilities. The train will have to go to COA for both. 15 minutes TAT is not sufficient for this. 30-40 minutes is a more reasonable TAT.
14:40...
more... is a more realistic time for arrival at COA. And with this arrival it can only run behind Circar/Ratnachal/Amaravati group.
6:30 hours is too unrealistic for BZA-COA-BZA run. Including the TAT at COA, 8 hours is more realistic.
All this is a moot point however. The train undergoes PM at BZA. So an extension towards RJY/GDV is not possible for now.