I used my assistant coach's skis last year(she's on the Nordica Doberman SLJ 150) they ripped, she's about 5'1" about 110 lbs I've got 25 lbs on her.
The Jr. world cups tend to have more than enough pop for a lighter weight skier (up to 145 or so lbs) Think how small j4 and j5 racer's are. I have two ladies that are racing on them now a Nordica dobberman SL Jr.( it's a 150 though) and another on the Volkl Racetiger Jr. race stock. I know that the Nordica changes it's footprint on the next size down from the 150 cm.
The Volkl stays the same on the 141 and the 148. Are you looking for chin height? Make sure you get a world cup or a race stock not just a Jr. race. Big difference in the pop and usually the side cut. The Volkl are FIS approved. But yes lot's of more petite women ski on the Jr' world cup and bonus they come in at half the price of their adult counter part!