The orange head is good, the black head is quite a bit better. The black head will cost more of course. The K probably needs some weight on the back for a 3-30, especially if you have to go over any steep places.
Both heads will shell corn. We ran orange heads until last year when we went to the black heads. The black head is a better head by far. It will cost more and I believe that it weighs a little more than the orange. Good luck!!