Please understand that I am not a BBer, but a strength athlete.
That said, nothing, and I mean no other exercises have added mass to my upper chest more than clean & press/jerk and the standing overhead press. I think that the key here is my technique. When I have the bar in the receiving position (resting on my upper chest/throat) I am looking up at the ceiling at a target I am aiming for when I press. This has the effect of slightly arching my back, and I get pec involvement during the press until I bring my head through my arms to complete the movement.
One other point, is that I am doing all of this with a 2" axle bar. I have no idea if that makes any difference, but I wanted to include that detail for clarity.
B-