i'd just work on upping his draw weight, at 14 he should be able to reach that draw weight in pretty short order... get him a bow with adjustable draw weight like a razor's edge, drop the draw weight down to 30 and start training, he'll be pullin 40 is a month or two...
I put this on your other post. You can get him a X-Bow package for $250 that will do the job VERY WELL. I agree with SevenMag Get him a Bow and let him build himself up. Plenty of good ones out there and not a whole lot of $$$