The BamBooBat Bamboo Wood Youth Baseball Bat: HNBBY Natural/Black would be a good fit for your son if he is swinging a 29'' 19 oz. The wood model might feel heavy at first, but will adjust quickly.
The BamBooBat Bamboo Wood Youth Baseball Bat: HNBBY Natural/Black is an approximate -5 to -6. This means if you purchased a 29'', it would weigh anywhere from 23 ounces to 24 ounces.
This bat would not be approved under the new USA Bat Rule standards used in Cal Ripken and other Little Leagues. When it comes to wood bats, only bats made of maple, ash, and birch seem to be allowed, while bamboo, composite wood, and other blended models are not allowed. You can find more information at LittleLeague.org.