Sheahan has been playing some really great hockey lately and is used to the down low, hard area work. He opens space for Nyquist and Tatar now so let him open some for Datsyuk. Maybe Nyquist and Z together will get both of them going. 4th like can grind down low the whole game and has the speed and skill to wear down the opponents. The third line I have no idea if it will work.
I don't mind trying those lines at all, especially if we aren't willing to call anyone up. If I was my choice I would go with
Nyquist - Z- Abs
Larkin - Datsyuk - Tatar
Richards - AA - Jurco
Helm - Sheahan - Glendening
It does a disservice to Sheahan who admittedly has played beyond a 4th line level, but I loved what AA showed while he was here and I want to see him play.