The big headed bit don't make one bit of difference, as my old mate used to say, big heads don't catch foxes, long legs do..!
Though so far, looks like I'm the only one who would go for the stronger type, half cross prefered. Must be of the right type though and all in proporton, bred from the right stuff, these types will be racey enough 'match fit', you only have to look to the genuine game dogs to see how they cut up.
I don't want a film star, just an honest dog!
Oh and lets not forget, without the halfs, the racy types wouldn't exsist.