Although the 308 does not have a huge amount of recoil, it hasquite a bitmore than the 243. Twice as much by some accounts.
Are you worried about the recoilbecause she has shown any issues with what she has shot in the past? You mention you have a 30-30. Does she have issues with the recoil on this gun? I can tell you the 243 is less and the 308 more than the 30-30

As far as performance, IMO for deer, both will be fine