Hi Larry A low mounted scope is best. Here is some info. http://rifleopticsworld.com/scope-mounting-height/ The lower the scope is mounted, and the closer it is to the axis of the bore of the rifle, the more likely it is to provide the consistent sight picture required for accurate long range shooting. Another factor is the longevity of the scope’s life. The higher the optic is the more force and torque will affect it during recoil. On higher powered rifles this can eventually wear out the scope, or simply break it.

while you want a low scope mount the problem is that if the scope is mounted to low you can not get you eye properly aligned behind it because of you cheek contact on the stock. The best scope mounting is where you can mount the rifle with your eyes closed, cheek on stock open eyes and be aligned with the scope

Always use the lowest scope mount that will clear your scopes objective lens and give you comfortable placement of your cheek position on the rifle(a comfortable shooter is an accurate shooter). Don't just mount a scope as low as possible solely for the sake of the lowest mount. The shooter is the most important part of the rifle that "You" will be an integral part of.

Also Larry, they make a youth version in a 20g model with a 13" LOP
Model: 32202, Youth/Small Frame
Gauge: 20 GA
Barrel Length: 22”
Finish: Blue
Action: Pump
Capacity: 5+1
Chamber Length: 3”
Choke: Modified
Sights: Bead
Trigger: Standard
Stock: Synthetic
Length of Pull: 13”
Total Length: 39 ¾”
Total Weight: 5.25 lbs