I already said u.. Most of the shatabdis ADI ASR KLK SC MAS Shatabdi do mps of 120 only.
And Nagpur-Sevagram strech too will become 130 kmph fit soon and rest of the route upto NK is 120 for LHBs, there is no problem.
Vidarbha is one such sf train with stops+speed both 60 kmph average but still travel time is 14 hours. so, CST-NGP Intercity too is expected to do 14 hours journey if started. If it needed then it would have got it long back, like kolhapur got Koyna Express
Intercity...
more... can be started for Bhusawal and for capital mumbai to second capital nagpur Shatabdi.
Now Shatabdi was given in routes like CST-MAO, PUNE-SC and hence CSTM-NGP too could be considered.