904 or 727

Thank you for the commets on my new ride, I can't due a 4 door but love the wagons how weird is that. The torque tube setup has been removed it has a open diff gm 10 bolt. Also want to swap that out with either 8 3/4" or 9". What kind of power can the 904 handle and would it bolt up to a new hemi if I go that route? I am thinking a sleeper.

Randy