Umm, couldn't you simply cut 1" off the youth stock? I think that the only thing you might have to do is relocate a couple screw holes. I'm planning on doing one of these for my wife, because she really likes my camo-lamo from Boyds, but they don't make a youth length. I'm going to wack off 3" or so and relocate the recoil pad.
I know that limbsaver makes a grind to fit version of theirs also and you can transfer the exact size where you cut it to the grind to fit one. You could use a slip on also, but would probably need a small instead of medium.