I agree with OR, stay away from 3-4 blade heads like the tooth of the arrow. You want something with max penetration, Magnus Stingers or Buzzcuts are a very hard head to beat in that category. You will also want to build him a pretty decent weight arrow. My wife and son both shoot the buzzcut and are shooting arrows with high FOC that weigh just north of 450gr.
My son does great at 3D and shooting spots with the same arrows he hunts with, the trajectory isn't great but they hit hard for that setup and the bow is whisper quiet.