Lennox Lewis was 'only' 6' 4 3/4" tall and is thought of as being a giant heavy. Yet David Haye, a 'small' heavy, is 6'3". Not much different. In fact, Lennox Lewis is closer in height to Haye then he is to either Klitschko. Lewis' height didn't make him what he was. His reach is more valid, but still, he had a dominant and at times destructive jab that plenty of people with that reach don't have.
Also, you say that half the punches he threw would have missed if he had an average reach, but as Adam alluded to above he wouldn't have been throwing shots like he had an 85 inch reach if it was only 79inch. He would have adapted.