I think your best options considering your height and riding experience might be more in ttr230 range. I've had friends with no prior off-road experience (outside of quads) that purchased 250 smokers and, even at heights closer to 6', they had tough times getting used to those bikes. It was just too much motor, and too racy (more hit and less bottom end like they needed).
I would just really attempt to get him to talk to some people who ride a bit and they could probably steer him away from making that type of decision. Btw, for a lady of your height, I know a lot of gals that really like riding ttr125's as they are hard to break, have very predictable power delivery, are easy to maneuver, and have a pretty low stand-over height. Most new riders will have the tendency to be riding at slow enough paces to, at times, need to put both of their feet down (particularly in trail-riding situations). A taller, heavier bike will be hard for a petite person to be able to do that with, and will end up in needless tip-overs and such, and will only push you away from having any desire to ever ride again.