This is a model set I don't use anymore. Seems to have overdeveloped muscles. I did proportionally-scale the figures to a height of 6' 1". But the chest, as noted, was barrel-shaped and the shoulders were a bit too wide. Thanks for spotting that. I have a different more-average model set today.
I did return to the model and narrowed the shoulder width of JFK and JBC. The open gap between them in the film (where we see the seatback) is now closer in width to what is in Z193. This must be the problem. I didn't change anything else on the figure models. The only other change I did was reorient the car relative to the curvature of Elm at that point. About a 1 or 2 degree change.
My limousine is not accurate yet with regards to the hand-holds and tire hump. So I removed the handholds. I estimate Kennedy's midline to be 7 1/2" in from the interior wall of the limousine. The rear seat is 60" wide.
This is not a criticism of your graphics, which you do really well, but the arm and chest position does not look natural and does not look like the photos. This photo taken on Houston Street shows a more natural position that is not have his armpit was pressed against the side of the car as you are assuming:
Also: you have to get the right distance between JFK's neck exit wound and JBC's spine. His spine was not pressed against the back of the jump seat. The distance between the neck exit wound and JBC's spine was more like 36 inches, based on the Croft photo:
Nothing much changed with regard to the trajectory hitting Connally to the right of his mid-line.
The Powers film shows JFK and JBC from the rear and has JFK's shoulder inside the car:
Something must have changed in the relative position of the two men after that for the trajectory through JFK's neck to get close to JBC's right armpit. [Note: the lighter area between JFK and Jackie appears to be the bouquet of yellow roses but the white spot just above that could be JBC's stetson - resting on his left knee?]
So I have JFK's midline at 7 1/2" from the interior side wall and the bullet arriving at Connally 13 1/2" from the same wall. About six inch difference. My jumpseats are 21" wide and about 8 1/2" apart. The center of a jumpseat is about 16" from the side wall interior.
I would have to move the Kennedy figure about six inches further away from the interior side wall to get the missile path to bypass Connally's torso.
You should estimate the range of error or uncertainty on the right/left position of JFK. The minimum is 7.5 inches and that has his right armpit right against the side (Canning measured the spine to armpit distance to be 20 cm = 7.9 inches on JBC). As explained above, there is also some uncertainty in the distance from JFK's exit wound to JBC's spine. It is at least 24 inches to the plane of the jump seat.
On the Hess & Eisenhardt scale drawing at 6 HSCA 50 the right jump seat is 2.5 inches from the side of the door which is about 1 inch further inside the car than the panel beside JFK. That makes 3.5 inches. But when I measure it, it appears to be 5 inches. The seat itself is shown as 20.5 inches wide so by that the middle of the jump seat would be 15.25 inches farther inside the car than the interior side wall beside JFK.
If you then assume just 30 inches between JFK's exit wound and JBC's spine, the bullet moves 30 tan(15) = 8 inches farther left. That puts it 18 inches left of the side wall using my 10 inch side wall to JFK midline figure. That is 2.75 inches left of JBC's turned spine. It could be a bit more. But even using your 7.5 inches for JFK's midline from the right side, that puts the bullet passing to the left side of JBC's spine by 1/4 of an inch.