I have seen it in Florence . There is part of the thigh that is unfinished because the block was too small and Micheangelo would not compromise at all I believe.
A possible interpretation of the 1/3 scaled up head and hands are that the mind and hands are the most emphasised attributes of us all.
He also wore dog skin trousers for months on end whilst he was ;in the zone '
and they had to be literally peeled of him! Great post
Thanks for these additional details!