Re: being a great body puncher doesn' t translate to being a great head puncher
Watch Tyson, at his best, when he throws his punches. He really drives off his legs and gets his weight moving so that he is not only getting it into each punch but his in a position to throw the next punch. Off the top of my head, I think the last flurry he threw against Pinklon Thomas would be a good one to look at.
The weight transference is also how you maintain balance. Danny Romero used to do an exercise (and I read about it and used it and it works) that emphasizes this. He would stand on paint cans and throw punches; if your balance is bad, you fall off. He was a very hard puncher, worth watching as well.