It is not that difficult to re-create the positions of the car and occupants using the zfilm and using an accurate model of the limo. From the SN, the angle to the car direction at z195 was about 13.5 degrees. At z224 it was 9 degrees. The separation between JFK and JBC was about 24 inches. The wound in JBC's right armpit was 20 cm or 7.9 inches from his midline. The exit wound in JFK's throat was .5 cm left of his (JFK's) midline.
Andrew ,using a lateral angle of 9 degrees, the exit wound in JFK's throat would be about 1 inch to the right of his midline, not 0.5 cm to the left.
The bullet entered at the base of Kennedy's neck at 2 inches to the right of his midline (Clark Panel). Approximating the length of the path through Kennedy to be 6.5 inches:
tan(9 degrees) x 6.5 = 1.03
2.0 -1.03 =0.97 inches
Do the math. The bullet traveling in a straight line from JFK's exit wound on a 9 degree angle will travel 3.8 inches or 9.5 cm farther left before it strikes JBC. So for the bullet to strike JBC's right armpit, his right armpit had to be 10 cm farther left than JFK's midline. So JBC's midline had to be about 30 cm farther left than JFK. Even if his shoulders were turned quite a bit more than he appears to be turned in z225 and even if he was sitting 21 cm inboard of JFK (ITEK said it was probably 10.7 cm and that puts him right in the middle of the jump seat), that is not enough. And that assumes the shot was at z225, an assumption that conflicts with a lot of consistent evidence.
tan(9 degrees) x 24 = 3.8
As you said, between Kennedy and Connally, the bullet moves 3.8 inches to the left.
3.8 - 0.97 = 2.83
If Connally had been directly in front of JFK and facing fully forward, the bullet would have struck him 2.8 inches to the left of his midline. Moving Connally 7 inches to the left , which the ITEK analysis allows me to do, the bullet strikes at 4.2 inches to the right of midline.
By rotating 30 degrees to the right, Connally moved the entry point on his back 3.25 inches to the left.
With Connally rotated at 30 degrees, the bullet strikes at 7.45 inches to the right of his midline. And I still have 1.6 inches to spare.