For a person to have "some head", they need to have either a single, outstanding, and/or abnormal feature on their head or just be an abnormally ugly or funny looking specimen.
This person has to be worthy of standing out in a crowd of people. He, or she, should be notable due to their courage and willingness to allow other see such a brilliant head.
To have a head is an honour in many countries. Ireland and Bavaria are good examples of where one can find a high standard of head.
Some head is an extremely flexible term, because by adding in adjectives between the word 'some' and 'head' you can adjust the term to suit your needs.
"Jesus christ, look at how ugly that guy is over there. Have you ever seen a head like that?"
"No boy, never before..he really has got some head!"
" Jaysus Boy. look at that outrageous head on that lad, looks like he came out of the Toys R Us Store"
" You have some award-winning head"
" You have some rotten head"