Well, that cage is a bit on the big side for a ball, but it can be worked with. You need to be sure the hot side temps and cool side temps are within correct range. You also need to make sure the humidity is correct.

At 2 1/2 feet, I don't think it's a baby anymore. By now, it is old enough and big enough to eat rats, the question is will she ? Start out by offering a rat that is the same size or a bit larger than the mice she eats now. Once she is eating rats regularly, you can slowly step up the size.

Gale