House Rule to Target the Whole Head

[phayman53]

I was wondering about making a House Rule to target the whole head. It seems strange to me that there is no way to aim for the "center" of the head and have whether you hit the skull or face be randomly determined and I would like to make one. This is mostly because, per RAW, hitting the face or skull is prohibitively hard in combat at realistic skill levels (12-14 being "professional" as per Tactical Shooting). This is not to say that every blow aimed at the head should be as easy to land as the torso, but -5 or -7 is REALLY hard. However, it seems to me that in most hand-to-hand combat with weapons, the head is often a not to difficult target that professionals usually aim for. So I want to make it a bit easier but still keep the RAW penalty for targeting just the Face or just the Skull.

My thought is to have the Skull, Face, and Neck rolled into one hit locations, the Head, with the sub area hit being determined by a 1d6 roll:

From the front:
1 = Neck
2-4 = Face
5-6 = Skull

From the back:
1 = Neck
2-3 = Face
4-6 = Skull

Then, if you are using the more detailed rules about face sub locations and arteries, you would roll 1d6 again to determine that effect (I know this is a lot of rolls and would not appeal to everyone, but I don't mind).

What I am wondering is what an appropriate penalty for the Head location would be. I cannot decide between -4 or -3. I am leaning towards -3 because -4 is the same as the hands, which, even together, are much less surface area than the head.

Thoughts on the appropriate penalty?