"Hunter's bump" is extremely common is SBs, partially because typical SB conformation predisposes them to it, and partially because pacing at racing speed is a terrific mechanicsm of injury to cause it.
I can't really tell from the photos whether it's hunter's bump or a roached back, but I suspect hunter's bump because of the horse's history. I also agree with the poster that commented on how uncomfortable he looks, particulary in the first and last photo. Might be because of other factors (cold, standing on asphalt) but I would definitely get his back looked at by a vet or chiropractor.
The other thing that jumps out at me is his front fetlocks - pretty typical for a SB that's raced, but those fetlocks are pretty thick and puffy.
Positives are a wonderful shoulder, attractive head and neck and a neck that ties into the shoulder well. Broad powerful chest. Both fore and hind legs reasonably square and straight.
Nothing here (other than the back) that would keep him from being a happy, healthy pleasure horse.