I'd buy whichever rifle, preferably lefthanded, and I'd immediately buy a ThunderBeast suppressor in a 7" configuration. Get it in 6-12 months and she'll love shooting that much more.
This in spades!
If I didn't want to invest in a suppressor I'd hold off on the 243 for a while and use a 223 of some sort.
The muzzle blast of a shorter barreled 243 can be offensive. I've seen quite a few kids turned off by shooting a 18 or 20" 243.
