He's not hugely upright, I'd just like to see a touch more slope (I am strange, I ride jumpers not dressage, but I still like a dressage-type shoulder). That kind of shoulder conformation is very common in the ponies.
If he's 14.2 NOW he may mature to be horse-sized rather than pony-sized, even if only by a tiny margin. At 3 1/2 he does still have the potential to level out but they've done most of their growing by then so I wouldn't rely on it. But he's not very much downhill so it's really no big deal.
He's really a very nice pony and I'd be proud to have him, if he was mine.