Here is a good video for shot placement I saw it on another forum.
http://www.youtube.com/watch?v=g9z7wb-iv5U
Also if going with the bullheads you may need longer arrows to avoid hitting your rest and this could affect the spine.
And if you do get them make sure you test them by shooting into something soft like a pillow so you don't damage the head.
Funny thing I plan on stopping in Missouri and Iowa this spring to try and wack one also good luck.