What were her XC 5K times? If she was sub-19, then she only needs 61 or even 62. I've coached the following:
A)26/56/2:10 (opened that season with 60/2:19)
B) 26/60/2:12/4:30/9:52/17:25(track)
C)26/60/2:18/5:18 mile/18:00 (track) (2:18 and 5:18 were a double about 30 minutes apart, so maybe in 2:16-17 shape fresh) This year already in 59 shape and we are shooting for at least 2:12 by June.
Put it to her that you two are going to explore her 800/1500 potential. Have her train for both and let the races sort out her real event. Get her in a few 4x4's as well.