his might give the increased relevance to the head part that you want. It won't double it, but it might possibly good enough for your sake:
MATCH (head, body) AGAINST ('some words') AS relevance,
MATCH (head) AGAINST ('some words') AS title_relevanceFROM pagesWHERE MATCH (head, body) AGAINST ('some words')ORDER BY title_relevance DESC, relevance DESC-- alternatively:ORDER BY title_relevance + relevance DESC
An alternative that you also want to investigate, if you've the flexibility to switch DB engine, is Postgres. It allows to set the weight of operators and to play around with the ranking.