Robert,
First off, my apologies for the delay in responding to this.
A couple of points to remember.
There is a downward slope to Elm Street of approximately four degrees from left to right from Zapruder's position that is not reflected in the image above. If you take that slope into account, the line you drew above clearly does not point to the top of the fence on the knoll at any time.
Secondly, and equally important, JFK's head at the time of the above image was determined to be canted to the left of the centerline of the limo by about 17 degrees - that is, JFK is not in profile, but is turned approximately 17 degrees to the left of a profile.
Thus, if you believe the image below as drawn by Paul O'Connor and the line you drew from the forehead to the back of the skull in the z-film link above correctly reflects the damage caused by a bullet hitting JFK's skull in the area of the forehead and blasting out the back of the skull, then it would appear that bullet should have been fired from the front-left of the presidential limo and on a plane with the limousine, not to the far right, slightly ahead, and above the limo.
http://www.internationalskeptics.com/forums/imagehosting/526994efb6f48a6d1b.jpg
Let me know if you disagree with that assessment, and if so, why.
Here's an overhead drawing reflecting the bullet path from the TSBD to the head, but if you reverse that line, it is the approximate path you believe the bullet travelled through the head (forehead to back of skull) on the horizontal plane, correct?
http://history-matters.com/archive/jfk/hsca/reportvols/vol2/html/HSCA_Vol2_0085b.htm
Now, do you really think that shot came from the Grassy Knoll?
Thanks,
Hank