Shuns are ground 50/50. The only thing left or right handed is the handle itself. If you own a right handeled model and you are left handed you can knock the handle off, turn it 180 degrees, and reglue it.
If you want a left hand bias, sharpen only the left hand side of the blade until you get the bias you want, 60/40/, 80/20, etc.
Japanese left or right handed knives are different animals all together, with a back side that looks flat but is actually slightly concave, and 99% or so of the sharpenng is done on the front side. As a lefty, I can't stand using a right handed knife as it is difficult to maintain blade alignment.
That's a very brief synopsis but should give you an idea.