In regards to a full sized vs compact stock, I do believe that the stocks are interchangeable between some of the Ruger/Savage/Tikka price points. Consider getting the full sized rifle but know you could get a compact take-off stock from fleabay or even the manufacturer that’ll bolt right on if the gun doesn’t fit the kid. Save the full sized stock and switch it back out after eats his Wheaties for another year or two.
Then again, you could also size up the .22’s length of pull compared to whatever you were looking for if the .22 fits him well.
I think
@SFC B works for one of the big retailers and could confirm if I’m correct about interchangeability?