Doing a domestic->Intl or Intl/domestic connection in BOM is a pain. You can do a OJ, flying into one of the southern airports and flying out of DEL/BOM or vice versa to shorten travel time. I don't think MAA/BLR(KA if its bookable)/CCU have an F cabin on their flights though. The CX forums say its the long haul J config but you should probably confirm that.

The North will be much colder in Jan though. Do keep that in mind while planning this.