head is way too big.

I quickly put the "head lines" (sorry for the pun) over one of my sketches. This drawing shows that the model was approx. 7 3/4 "heads" high. Which is pretty normal. However, most artists consider 8 head lengths to be "ideal." I do too. It was just that this particular model was a little stockier. I don't consider the loss of 1/4 of a head length (off of the "ideal") to be too unacceptable in this case. However, if the model were drawn any shorter, the drawing would probably not look too good.

In reality, most people are about 7 1/2 head lengths, or even 6 1/2 head lengths. But this just doesn't look "right" when drawn on paper. So, it is acceptable (and strongly encouraged) to heighten the figure a bit. 8 head lengths is the recommended standard for figure drawings (or even 8 1/2 heads, if the person is very tall and "heroic").

Even if your model really is 6 1/2 heads high, it is very likely that your drawing will not look right if you stick with the 6 1/2 head proportions in your drawing. Everyone will tell you that you made the head too big. Just draw the figure 8 heads high (or 7 1/2 is okay). Everyone will tell you that it looks "just right," even though you'll know that it isn't, strictly speaking, accurate for the model.

The "heads" should align on most figure drawings this way:

First head length: head!
Second head length: chest line at nipples.
Third head length: waistline, at bellybutton.
Forth head length: groin area.
Fifth head length: a bit above the knee.
Sixth head length: just below knee.
Seventh head length: above ankle (or mid-calf, if the person is 8 heads).
Seven & 3/4 (or eighth) head length: at bottom of feet.

Haha, yep, but that's what they asked for, more specifically 7 dwarves and a wagon traveling through a mountain road. False advertising? I guess.