Try the Sea Soft Pro BC. It's a jacket style BC and is fully adjustable from XS to XLg!
Laur, my wife, is 5'3" (I'm being genreous). I', 6'2" and 240 pounds. When my Genesis Recon dump valves failed on me recently, I borrowed her BC, adjusted it to fit me and made a couple of dives!
The weight ingtegration is about the most sane on the market, too. No fumbling with pouches and special hook in locks. The Sea Soft Pro has big pockets with zippers on top. Drop in the weight you neede, zip up and go! The bottom of the pocket is the quick release.
They're not cheap, but they're really well made and your son may not need another BC until this one wears out!
Here's a weblink for you:
SeaSost Pro BC
No, I am not a Sea Soft dealer or salesman. I just replaced my Recon with a SeaQuest Balance. I prefer a back inflate BC.
Ian