I don't know how it's targeting if contact is below the face mask. The face mask extends to at least the chin and I don't see how it's possible to get a shoulder pad below that and hit the QB in the neck.
DQ? Would the same tackle be a DQ if the QB still had the ball?
It's a PF, don't make it something it is not.
The definition of "Targeting" (NFHS 2-20-2 starts out with a very specific, "unique" description;
"Targeting is an act by any player who takes aim and initiates contact:" which......" suggests both deliberation and intent. Another foul, which suggests specific intent is "Flagrant" (2-16-c) both of which add a judgment, of what is observed in that unique instance, which separates from and goes beyond other fouls.
Either foul allows for disqualification, when the excess application is obvious & clear. when that certainty is questionable, as suggested above, PF seems the more appropriate solution.