My upper chest responds well to the incline bench. I know some people hate to use the smith rack, but if you want to do some slow, controlled rep movements to really try to stimulate the target muscle group, sometimes the smooth movement along the rails is helpful. I would consider doing some angle "pyramid" sets (high reps), with each set adjusting the degree of incline.
For example, smallest incline 135 x 15, next smallest incline 135 X 15, and so on. Progress to an incline that is just starting to work shoulder and stop, and then move back down. You'll get a lot of reps, get a lot of blood flow to the target area, and you'll get the "feel" you want when you're attempting to target the upper pecs. The mind/muscle connection is no joke.
Good luck. You've got a good base.