Typical of the breed, he is sickle hocked. In a draft breed it was thought that such conformation would provide more pulling power. In reality it provides for more spavins in hocks. His front legs are over straight IMO and his shoulder is steep, but he is very young. A wise phrase I have never had fail me is this one when judging a young horse, "Tops may come, but bottoms never!" This says that if a horse has crooked legs, they will stay crooked... but if he has a somewhat less than stellar body type that may change for the better.
That being said, I do not know what you mean by show horse. You mean in the ring as a halter draft horse? Do you have an example of a Shire you know is winning in this that you can post? Halter classes are odd in that horses that would not make it as working horses can win there (look at the Quarterhorse for examples).
There is something about the outside of a horse that is good for the inside of a man. ~Winston Churchill
) Dinosaur Horse Trainer