As a coming three year old I find this horse a bit body heavy and under legged. Legs are too fine and the body is very QH. Neck is set low and I think he is not as downhill as this photo indicates. He is tied in at the knee and light boned below it and may even be a little back at the knee. Hocks are small but placed well (low) as are his knees. His shoulder is steep but the point of shoulder is relatively high (for the breed) so he may be ok there.
Yes.. his pedigree way back is very nice.. I know those horses! However, the first 3 generations are what really count. Have his sire or dam been raced or used for anything? Do they have a Speed Index?
Ultimately, the back breeding may come thru.. but with each generation of horses with no records between those good ancestors and the horse on the ground, the chances of that happening are reduced.