There might still be some room in Q for more human male heads. I already found one dupe among the nordic helmed heads, making me believe there might be other dupes that can be overwritten.
Two other (not ideal) possibilities might be:
1) Using heads 50 to 99. They would show up during character creation when numbered sequentially but not in the toolset, which would require builders to use scripting to use them for npcs (to make it a little more convenient, a catalogue with pictures of all those heads and their plt info could be added). I guess it could work similar for heads 200 to 255 (though players can't choose them either, I believe).
2) Adding new heads as helmets. As far as I tried this, it works quite ok and just requires renaming. Not sure if this is possible, but maybe the helmet entry in baseitems.2da could be cloned and the copy renamed to Heads (Human/Male). Of course, this is not a good way to provide players with access to them.
2.1) Making helmets out of the helmeted heads added with Feanors Armory, freeing up space for other heads that way.