Yep...you will get a-lot of varying opinions...but...whichever one you get for her...make sure you put a good recoil pad on it...like a Limbsaver..or Pachmayer decelerator..and also add a nice soft cheek pad as well...if it still kicks to much...tame it down by adding some lead shot in the stock bolt hole...you can tame even the the largest hardest kicking ones down this way...using full house loads...
Now...caliber selection...anything over the 223 will be a step in the right direction...even though the 223 is adequate for close range perfect shot placement shots...and the 243 would be a logical step up from it...but...here is something you can try if you have a 270 or 30-06...let her try out some of Remingtons managed recoil loads...Everyone I've talked to in person that uses these swears by them doing just as the claim they do...and are getting pretty good accuracy from them...and around here they are having a hard time keeping them on the shelves...they work...and work great...and is a alternative for you to look at.
Only 1 problem with doing this...she might like the combination soooo--much...you might have to get another rifle
...but sometimes that isn't so-bad... :wink:
While I think the 44 mag is pretty good round...and the 357 is ok... but before I went that route...I would go for a good ole 30-30...the recoil isn't all that bad...and it is a great medium range whitetail round...and ammo can be had just about everywhere...
IMHO...if you do elect to go for the 243...get the 24" bull barrel...they seem to give the best accuracy...and the extra weight can be a aid in shooting off hand with it...while it's not as easy to carry for a small framed person..a pound or two shouldn't matter a whole lot..
1 type of ammo I would try for either one...is the new Federal Fusion they make it for both the 243 and the 30-30...I haven't shot any in either caliber...but Quickdtoo has in the 243...and it seems pretty accurate...I have shot it in my 30-06 Ultra-Comp and get exceptional accuracy...so..it just stands to reason the other calibers might be pretty good too...
Good Luck...
Mac