So... pick him. :D With 5 Star and 5 Potential it won't be a 'wrong' pick. And Height will affect his training, but not his skill on the courts. So if he is beasty at the Power Skills already, sure it might take a little longer for them to pop... but they will still pop.
Not sure how much his Height will slow down Big Training, but if he's your centerpiece then you can One Position Train to help keep it fairly fast.