Agree with the previous poster. More important that height of the horse is correct conformation with bone and substance. The type of horse you're looking for is sometimes referred to as a Man's Heavy Weight Field Hunter, and is usually a draft cross. There are plenty of people your size who do ride and enjoy it and do not 'kill' the horse. Unfortunately, a horse of the size, bone and substance to comfortably carry you will probably carry a premium price tag.
I think, at 6' 7", you're also going to want a horse with a substantial barrel, and a lot of depth through the heart girth, so that you can actually put your lower leg *on* the horse and feel secure.
If you're concerned about how your weight affects the horse, there's some general things that you can do as a rider to help. (Actually, *all* riders should do these things, but they become critical for larger riders.)
Never mount from the ground if you can help it. Stand the horse in a depression, use a mounting block, bucket or stool. The stress and torsion of mounting can damage your saddle, and pulling on the saddle as you mount can hurt the horse's back. In addition, practice mounting lightly, catching your right stirrup and standing up for a few strides while allowing the horse to walk forward, then slowly sitting down.
Make absolutely sure that the saddle fits the horse and you. Any saddle fit issues will be exacerbated by the extra weight.
Avoid spending a lot of time riding in full seat. Alternate riding in full seat with half seat or posting.
Make gradual transitions. Don't slam on the brakes to halt, or expect the horse to accelerate like a sport's car.
Good luck, and hope that helps.