My first impression is that he's been ridden badly for a number of years - his neck muscling is rather pathological. (I hope this is a newly purchased horse - if he's been yours for years, I apologize but that truly is how he looks). If he were my horse I would put him in a snaffle and ride him on a light rein with his neck and head relatively
low until he lost those muscles and learned to get his hind end up under him (conformation allowing). *Then* the rider could ask him for somewhat higher head carriage. This is a good example of things that happen when people have a preconcieved notion of how high a horse's head should be and/or what bit he should be ridden in
The hammer head (its size may be partly the photo angle), the narrow chest, narrow base, cow hocks and toeing out don't actually bother me a huge amount in a KMSH since IME they're fairly typical for the breed and presumably this is meant for a pleasure horse (as in, riding for pleasure) rather than a grand prix jumper or anything like that. His shoulder is straighter than what I'm used to seeing on KMSH's but its shape and set are typical of the breed otherwise, and again, if this is meant as a horse that you just ride around and enjoy I don't think it's likely to limit the horse's usefulness.
L hock (can't see the R one) *may* be a bit boggy or perhaps spaviny, but it is really hard for me to tell, and again the hind fetlocks *may* be a bit enlarged, all of which would be consistant with the way his breed is often ridden and the way his neck looks. Even if what I'm seeing is real, no way to tell from a picture whether there's much functional significance in terms of soundness. No other obvious unsoundnesses (tho I wish his feet were bigger and perhaps shapelier), and other than the neck muscling he looks in ok shape.
I haven't had really worked with KMSH's, but the ones I've met, plus related breeds like tenessee walkers and saddlebreds that I have worked with, generally have very good levelheaded brains and are a pleasure to deal with, and I see no reason to think this guy would be an exception
Have fun with him,
Pat, really not a big fan of the breed, but observing that they seem to work out fine as recreational horses, so I'm not sure how much point there is in getting all hung up on biomechanics or conformation with 'em