My vote is SHOW HER.
I'll agree she may not be stout enough for the Commercial classes, but if she is fed & fit to show for the next 18 months, she will end up as a bigger, more gentle, healthier replacement heifer. And, she won't be too heavy muscled to have a calf.......like most commercial show calves.
Now I'm not saying she won't work in the show ring. She is mighty green. I would like to see her at least 600 lbs. at this stage. She may be a little pinched in the heart, but may also grow into it. Don't worry about her front being trashy. I can tell that most of that is hair, plus her head is not up. She is actually pretty nice in the front end, and how she ties in to her shoulders. She could be standing on more bone to show with the commercials, but that too could change with a real good nutrition program.