Looking at the images I would suggest the problem is the head and lekku use two different materials, its like trying to make a glass vase appear identical to a ceramic pot by just changing the colour, light interacts with both differently so they will never look the same.

If this is the problem then you could take a copy of the head material and paste it to the lekku but then the problem is the head texture will also be applied (complete with eyes, nose, eyebrows and other non lekku type features).  To get around this you could use a paint program to take a swatch of texture from the face image (eg forehead) and use that swatch as the texture for the lekku (maybe tiled to prevent stretch) - may be I've mistaken what Ockham's meant but that's my take anyway.