MyLittlePonies, I wouldn't worry so much about your mare's age and her being able to foal a big foal. 99% of the time the foal only grows as big as the mare can handle. Your mare is wide barreled with wide looking hips....she would be able to get a foal out by a draft stud easily, IMO. (if you can call labor easy. LOL)
Good luck on picking a stud! No Doubt I'm Lazy is gorgeous, and it looks like he passes it on...his babies are gorgeous, too!
A good horse is worth more than riches. ~ Spanish Proverb