shaun : i think he means he can easily measure a heavier weight bow...or he has one on hand that the lad can use , but wants to know if it will do the trick.
if youre making a bow for him , i would work it up to about 45# @ 25" . that way can just use it now and will grow into it.
are you indeed making a new bow or lending one of yours perhaps?
i would get a luggage scale (about 8$ from wally or martK) , and see what kind of weight you are pulling at the drawlength.
shaun does have a good point , in that someone using a 28" bow at 22" is essentially short drawing. doesnt mean its a bad thing , but you will obviously see a loss in performance from the 28" draw...
-hov