I really like him, nice shoulder with a well formed hind end. I would like to see what his angles look like when he stands square in front, but at this angle, I would like his neck a bit longer for such a big framed horse.
I don't think you can really tell jumping potential from a conformation photo. You say he loves to jump, so free jump him over some grids and you should be able to get an idea. See how approaches things and has a natural ability, though under saddle things could always change
there is a very good jumper confirmation discussion given in the George Morris Horse Mastership clinic video. He compares Gem Twist and others, and discusses / compares him with other jumpers confirmation, and talks about the angle of the point of the shoulder, to the wither, that a steep angle is best, and the jumper bump, the point of the rump to the top of the hip, the height of the hips, etc. it is very good. the video is expensive but you can rent it from barn sweet barn dvds.