You didn't say how big your boy is, but my next 22 will be a Savage Mark ll Classic T (T for thumb-hole stock). It's a bolt action with a 10 shot clip, so you can't rip through the bullets like a semi-auto. I like it for a number of reasons.
1) It has a 24 inch barrel, so the velocity (and PB range) will be better than anything with a shorter barrel.
2) It comes with Accu-Trigger, which is a definite plus, if you remember to put the safety on.
3) It has a thumb-hole stock, which isn't quite like a pistol-grip, but still puts your wrist in a more comfortable position.
4) Savage has good accuracy right out of the box.
It weighs 6lb 3oz, which may be a little heavy, depending on the size if your boy.
They make the same rifle with a conventional type walnut stock, which weighs the same.
http://www.savagearms.com/markII_classicT.htm
If your heart's set on a single-shot, disregard the foregoing. lol