Do you have any references for 'head cults' in Europe? Can't remember where I talked about them but it might have been St.Trillo's skull in Wales - if you drank water from the well in the skull you were cured of whatever, apparently it journeyed to Australia in the hands of the "guardian" but eventually came back in 1970ish. From what I remember I think it turned out to be a female skull -which rather squashed that story.
Anne Ross, in Pagan Celtic Britain has a whole host.... the one that sticks in my mind is Rocquerperture, the door frame of the sanctuary, has niches cut for the skulls. The head was seen as the "soul" point, the essence of the person. In a British context, the Welsh Mabinogon tells the tale of Bran the Blessed, in a tale too long to tell, but he is mortally wounded, and he tells his warrior to cut off his head. This head is able to talk and eat, and for 7 years I think lives on, at one point in the otherworld, its final destination is to be taken to London to protect the country...
In roman Bath, the famous "celtic head" on the shield, is probably one of the finest carvings in the country.. There is evidence of heads, worshipped or venerated during the roman period. Caerlon, and up north in Yorkshire, there was also a celtic head type found in the foundations of a roman house at Camerton. Also evidence that when the roman statures of gods were overthrown, their heads were "decapitated". Minerva at Bath, and also at the pagan temple of Uley..