Sorry to say, but I think you just committed sacrilege. Part of the appeal of the Enfield is the sound given off by its engine: it idles slowly enough to count the strokes, and even in fifth gear, it sounds pretty laid back. The KLR 650, while a decent enough all-purpose bike, can't hold a candle to the aesthetic appeal of a Bullet. Its stroke is too short, its report too high-pitched.
Remember, these bikes are works of art as much as they are vehicles. A Kawi engine would ruin a good portion of the Bullet's artistic flair.
EDIT: In spite of this, I wouldn't mind seeing a big-bore mod like the one available on the old Iron models. Yes, I am a dirty hypocrite.