KShunter, Browning does offer a 243win in Micro Medallion in a lefthanded action. Yes the BOSS will reduce the recoil but it also is LOUD and must never be shot without ear protection unless you want to sustain ear damage, something to be considered when choosing a hunting rifle! Have you thought about a 7mm 08? It is mild recoil, I know a number of youth/women who use this chambering with no problems. It does offer some advantages over others in the low recoil class in way of the .284 bullet used and best part no need for a brake or BOSS to be used. I also suggest buying and installing her a good recoil pad, this will make a difference vs the factory ones most rifles come with when it comes to felt recoil.

Best of luck.