He is 4'11" or so and weighs 74lbs soaking wet.
Recoil will be an issue.
Stock fit, rifle weight and the energy going out the muzzle will all play a role in perceived recoil.
A stock that fits, with a sight (glass or iron) system that allows a good cheek weld, are important.
Youth guns are great ...... except the flimsy plastic stocks most of them come with weigh almost nothing, contributing to more recoil .....
A good youth gun needs to be short enough to fit the youth, heavy as the kid can handle, and loaded so as not to beat them up ...... if you handload, caliber chosen is nigh irrelavent- most chamberings can be downloaded for begginners ...... however, choosing one too small for future uses can't be so easily fixed.
My solution for a kids' gun was a Ruger Frontier in 7-08 ...... downloaded to 30-30 levels to start with. Works well enough that they argue over it.