This shows an angle of the bullet path to the car about 8 degrees. I can't get anywhere near 8 degrees at z224. It is more like 12.5 degrees. Besides, this shows JBC with his head out over the console https://www.jfkassassinationgallery.com/displayimage.php?pid=1339&fullsize=1 the jump seats and has his shoulders turned quite a bit right from forward. That does not fit z224 that I can see. He is facing forward at that time.
I just checked the angle using the following method. Don Roberdeau’s map shows the limousine’s locations at various times including Z207, Z225, and Z247. An arc would be required to connect these three points. Therefore the limousine was turning towards the left during the time between Z207 and Z247 (not traveling in a straight line). I drew a straight line between the points labeled Z207 and Z225 and extended it substantially past each point. I did the same thing for Z225 and Z247. Z224 is close to halfway between Z207 and Z247 in time and distance. Therefore I believe that a line that bisects the angle between the first two lines that I described earlier would be very close to the direction of the limo at Z224. I hope that you can follow all of that. Another line between the point designating the rifle in the sniper’s nest window and the point designating Z225 would represent the path of a bullet aimed at JFK at that moment. I measured the angle between the bullet path and the limousine direction at Z224 to be 8-degrees. The angle between the bullet path and the line between points Z207 and Z225 to be 12-degrees. And the angle between the bullet path (@Z225) and the line between points Z225 and Z247 to be 2-degrees. So it appears to me that Don Roberdeau’s map tends to agree with Dale Meyers’ calculations. And perhaps your results don’t take into account the curved path of the limo.
Also, JBC is not facing to the front of the limo at Z224. I believe that this set of Z-frames might help clarify the actual position of JBC during this time period. His right shoulder is difficult to discern from what I interpret to be shadow behind and to his right of that shoulder. Which tends to distort the perception of his actual position.
https://www.jfkassassinationgallery.com/displayimage.php?pid=1339&fullsize=1
It is important to try to get this right. Here is how I determined the angle. I used a scan of a scale map of Dealey Plaza that is provided by Richard Trask in his book Pictures of the Pain.

1. I located JFK at z223 on the map. Since at z225 JFK is just past aligning with the corner of the west retaining wall from Zapruder's position, I conclude that he would have aligned with it at z223. So I locate JFK at z223 at the intersection of a line from Zapruder to the corner of the west retaining wall (purple) and a line following the path of JFK at z223 (blue line). [Since the left side of the limo was close to the left side of that lane, JFK would have been about 6 feet from the left lane marker and a similar distance from the right lane marker.]
2. I then draw a line (red)from the SN to the position of JFK at z223. I extend a line from the SN perpendicular to the blue line (green).
3. I measure the sin of the angle by measuring the length of the green line and divide it by the length of the red line to the point of intersection at the JFK z223 position.
As far as the shoulder direction of JBC at z225 is concerned, I just don't see much of a turn, if there is any at all. Perhaps we could estimate the possible range of angle. I would say it is anywhere from 0 to 10 degrees right.