This is where I would be at if I was in your shoes, doesn't mean it would be what's best for you though.
I'm partial to the .270, that's what my daughter shoots. She can handle the full power ammo, but for where we normally hunt I let her shoot reduced recoil loads (100 yards or less on 200lbs whitetails). For an elk hunt I would make her go with the full power load in the .270. She shoots my 300WM, so that wouldn't be an issue now with what to shoot for her. As an FYI, she's 16 and 120lbs so it's not like she's big. She has no fear of any recoil, she'll pull the trigger on anything she gets behind.
I'm partial to the .270, that's what my daughter shoots. She can handle the full power ammo, but for where we normally hunt I let her shoot reduced recoil loads (100 yards or less on 200lbs whitetails). For an elk hunt I would make her go with the full power load in the .270. She shoots my 300WM, so that wouldn't be an issue now with what to shoot for her. As an FYI, she's 16 and 120lbs so it's not like she's big. She has no fear of any recoil, she'll pull the trigger on anything she gets behind.