As one who is "cranially gifted" and a former model I can say that it really depends on the person. Sometimes I get shit from people for the size/shape of my head but on the other hand I have my share of guys and girls hit on me too. Must not matter that much. So, I say if you have a big head who cares?
Seriously, just learn to work with what you've got. If you think it's unattractive then that is the vibe people will pick up. The same is true of confidence.
Live your life,find someone who is attacted to you not just a physical attribute that you can't do a damned thing about, and if people give you shit for the size of your head, tell them the one in your pants is bigger and they can suck it! LOL!