Head size is relative and is dependent on the tyer's own sense of porportion. There is no hard-and-fast rule on head size. It is important to have a head that is well-formed (and McCorder's are very well-formed) sort of in the shape of a Hersey's Kiss. The are many other famous tyers who tie larger heads, Ron Alcott comes readily to mind.
To answer your question on space between fly's head and hood eye, yes, it is fairly typical of the better tyers here on the west coast of the US to do this. The reasons for it are: 1) when a hitch is placed on the fly it is placed farthur back on the shank and causes a more erratic fly action: and 2) it allows a fisher to tie a whip finish knot behind the eye, which is stronger than a Turle.