I like him. He looks like he has a QH butt lol. Nice and muscled. Here is what I see for confirmation:
He has a nice long, sloping croup. I like to see this in jumpers
He appears to be either Butt High (possible since he is still a little young) or built downhill which will only make collection and working from his hind end harder, but not impossible.
His shoulder is nice and the length of his arm is also good for low level jumping.
I really like his hind end...not normally impressed so much by a TB's hind end but I really do like his butt.
I def think he would be good for low level jumping and I actually think he could go higher than low level (like intermediate jumpers) The only thing to watch for is that he stays sound. I've seen too many OTTB's come off racing fine and start jumping and develop problems. Its unfortunate since it happens a lot from the stress of racing. Either way I think that if you like his temperament and want to adopt him than go ahead and do it. Unless there are any unmentioned health issues in his legs than I think he's set to be a jumper. Good luck!
PS I love the name Gambler.