I used to ride a wide Qh/arab cross that I was training for a friend. He was 14.1 or 14.2 and I'm 5'6 and fit him easily-- didn't look too big on him at all. He started out as more of a pony mover, but as time went on and he relaxed, he started to lengthen a bit. My friend got him free, and while he was definitely not AA material, he ended up being a great little packer. So, while I haven't seen this one, it sounds like you really want to go for it
My first trainer had a very cute 14.3 hand Welsh/TB/QH/Arab gelding with a big stride- he was awesome for us kids as well as the smaller adults. My trainer hunted him as well (she was 5'6") with no trouble. He was stocky, but not super wide.
My trainer friend just asked me to find her leads on a good lesson horse in the 14.3-15.1 range. She wants something that can be ridden by most students, and this size works well for nearly all riders.
My favorite lesson horse was a 15.1 gelding, thought to be a Morgan x Percheron, but could have just as easily had QH in him. I LOVED that horse, wish I had a clone of him.
My old barn had a 15.1hh TBxPercheron that they put into the lesson program when he was on the young end of five. At first he had the more advanced riders on him but he was so steady that within about two years he was giving adult beginner lessons. And with that Perch in him, he's pretty sturdy and can handle the heavier adults.
"Things turn out best for the people who make the best of the way things turn out." ~John Wooden
I think especially for beginner riders or older newbie's smaller makes them feel much more secure. If he seems to have all the other ingredients that you are looking for priced at a negotiable $300, I would give it a go. If he doesn't pan out after some tuning up, sell him.
I am no newbie rider but LOVE the smaller horses that I fit on. At only 5'3 that isn't hard, but I find a hard time getting my legs around ponies that are fit. Morgans are a great breed too! Let us know how he works for you
At my barn the two of the favorite lesson horses for adults are 14.2 and 14.1--a Haflinger and a welsh cob, respectively. I am a little biased because these are mine, although I am not the BO and several trainers other than me use them for adults, by rider's choice. I think they are chosen by a lot of adults because they are super-cute, gems on the ground, and great confidence-builders (not that there isn't some evil pony that leaks out at times). They do have nice gaits. In fact, folks come from other barns to use the Haflinger mare for her infamous relentlessly rhythmic big trot to learn to post. And, at the end of the day, you can't ask students to ride bareback or without stirrups on just any old horse--it takes a special horse and a certain level of confident/comfort on the part of the rider. But you can on these guys. Hey, I, too, like to sneak in a low jump school bareback on one of these when I can. I need the training for my body, but I'm not quite brave enough to go bareback on my big green beans.
Looking forward to the photos... And if for some reason he doesn't work out long term as a lesson horse, he could have a great future as a well-broke, all-around competitive trail horse. The trail-riding demographics skew older and a well-trained smallish horse could easily find a home with some old lady who will give him the best of care and keep him forever. Ask me how I know!
It's just grass and water till it hits the ground.