I get the same pain your describing and I'm 6'3". I was a swimmer in my younger years so I've got minor issues with my shoulders.

I add the ($30) BigBikeParts risers which helped but I still get the pain. There is another more expensive set ($80) from MLB that I've never tried. I don't think the more expensive MLBs, or the Kuryakyn, risers will change the angle that much and I haven't be willing to spend money ($900) for Helibars.

Here's what I do...Obviously, the cruise control helps a lot. Being able to let the right arm hang or putting my right hand on my right hip usually relieves the pain. The other stretches' I do while on a long ride are: 1. Very deliberately turning my head 90 degrees to the left and right so It touches each shoulder. 2. Focusing on pushing my elbows are far down as possible. 3. Lastly, and this seems to be counter intuitive, "shrugging" my shoulders up high around around my head for a minute or so.