You can forget about the chrome lining unless you are going to make the rifle full auto, and I highly doubt that is going to be the case. In fact, chrome lining detracts from accuracy to some extent.
Now think about your barrel profile. Is she going to be shooting prone, off of a bench, standing? If this gun is to be fired solely from a bench or prone, I would think at least an H-Bar barrel or a bull barrel would be appropriate. But if this gun is to be carried alot or shot standing up, that rules out the bull barrel option. Far too heavy.
Now distance shot......out to 200 yards, any option between 16 and 24 inches will fire that distance accurately, so pick your poison there.
Rifling twist......if you are going to fire only commercially bought ammo, which I believe is of the 55gr. variety, you might want to stray towards 1:9 twist. If you are going to roll your own ammo, and want to shoot something a bit heavier to buck the wind better or maybe go a further distance, then look at the 1:8 twist barrels.
Now remember, all of this info subjective, but hopefully it helps you get started in the right direction.