Honestly, no horse has perfect conformation. QH's and APHA's are very diverse in build for breed, according to their use. HUS horses are lanky, and long (Mine's not, but he's got great movement). And you'd never dream of using a halter horse for any real rugged work - well most of the halter horses - some of them have pathetic excuses for legs.
Really I don't see anything majorly wrong with her, and even though she's bred to rope, she's still classy looking and better looking than most broodmares you see popping out foals every stinking year. I say go for it. Even if the foal gets the worse of both parents, it'll still be a nice colt I think.