bull,
sure 2 3/4 will get the job done. Make sure she keeps the distance short. Without doing any patterning myself I would guess no more than 30 yrds. Buy her a limbsaver recoil pad, and you will also appreciate it when you use those 3.5" 2 oz shots. Just buy a few boxes of different shells and a good choke and see which one will give you the best 2 3/4 pattern. I doubt you will be able to get anyone to give you any specifcs especially with the 535 since I have a hard time getting info on this newbie. Let us know what shot/choke you go with.