My suggestion is this, go to a few BOW shops, and ask them what they feel is good for him/you, there are tons of great bows on the market and there is NO need to buy the latest and greatest bows either, countless bows of the past decade are great bows(at one time many were the latest and greatest)
so don't rule out buying a used bow from a bow shop, as MANY MANY hunters trade bows in every yr to be the cool kid with the newest bows out there , and that means great savings on there like new used bows!
Bows have HIGH market up(I sold them so I kind of know this for a fact)
so when folks trade them in they normally take a beating unless being over charged on new one!
this again is why many bows sell privately over trade ins! and why trade ins have low values to bow shops, there kind of like new vehicles, as soon as your off the lot there used and worth a LOT less than you just paid LOL
But due the size of your boy, you really need to go to a local bow shop'/shop's, and get fitted properly to know what will fit him best and those make him shoot it the best
LOWER BRACE HEIGHT"S bows are easier to shoot well with, more forgiving, so IMO< they would be the TYPE to be looking for 7 inch or longer brace heights are what you want to learn on, you will learn faster and be better at things faster, and if down the road, you wish to upgrade, so be it,
why spend a TON getting into a sport you maybe won't like! again reason for a used bow over a new one as well!
if you buy used from a private seller, just have bow looked at , at a GOOD bow shop, have a new string put on, and overall bow inspected, and set up to FIT your boys, draw length, just DON"T buy a bow till you know what he needs and then stick to bows that can handle his set up needs(draw length, LBS of bow draw weight and so on)