The easy answer to follow up shot placement is "anywhere you can hit them".

With Buff and Ele on an angling away shot you will obviously lead and try to hit the heart lung region if available--

If it is more of a straight away shot with a solid where will you go for-- a haunch to break the pelvis/hip, a Texas "heart shot" from rear to forward, or try to spine 'em high from the rear. If you go for center of mass going away then you may have to go thru the stomach full of food, etc, slowing the bullet down MUCHO .

Where you gonna whack 'em with a solid running straight away guys??