Any 2 blade Cut on Contact head that’s constructed well in 100gr will be good. Stay away from mechanical and even 3/4 blade heads. A good option would be Magnus Stingers for a budget friendly head with good quality.
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.
Just for reference, my wife uses vipertricks. Pass through on javelina at 25 yards. Didn’t pass through a mature white tail buck at 15 but that wasn’t a perfect hit (clipped spine). Shooting low to mid 40s (I think 45 but not certain). Perhaps the stingers would have done better on that buck.... (it didn’t go far and we did find it, but blood trail was tough)
My girlfriend has achieved pass throughs (40#-52#) on several whitetail with Solid Legends and Day Six Evos. I would look at a head of this style coupled with an arrow that is substantially heavier than what most SD archers tend to shoot.