As an Ectomorph, is there any particular gym routine that would be most effective for upper body growth?
You can't just look at upper body growth. Aim for full body growth inc legs and back.
Do heavy compound movements. Such as bench press for chest.
Shoulder press for shoulders.
Dead lifts for lower back.
Pull ups and bent over rows for upper-back
Squats for legs.
Sets/reps of 3 x 8–10
And 5 x 3–5
The most important factor will be to eat big and clean.