He looks like a typical ottb (I've now worked with three in the past year). As he calms down from the track, starts to get fat and happy, his muscling will change. His confirmation looks typical (but it's a little hard to tell without more photos). A lot will depend on why he left racing, his soundness, etc.
However, I have seen many of them retrained for eventing, but what I've found is you're just going to have to play with him to see what he wants. One of the first things we did was lunge the horse to see movement, and then lead over a small jump while I ran along side. This usually gives a good indicator of the personality - a brave horse will go right over it, and a more careful horse might duck out (make sure you're prepared if he decides to run around the jump). The first time I lead Scout over a jump, he landed and bounced around because he LOVED IT. After I established that he enjoyed it and was physically capable (until the Laryngeal Hemiparalysis was discovered), we began with jumping basics - ground poles, small cross rails (really, only 6 inches in the middle).