Your LN 3 shot, 3 hits, theory at least makes more sense than one where the TSBD shooter (whomever he was ) would in a sudden panic , stand up and attempt an early unaimed shot FAR off enough to miss the entire right SIDE of the limo( as per the photo of the LOS perspective from the 6th floor SN window that you previously posted).
At Z190, I do see that JFKs back and neck angle may be more vertical relative to the horizontal line of the limo, as he might have moved his upper back forward thus not leaning so much back in the seat as he was at Z224. But I’d like to see an experiment with dummies to test out the shot and see if it aligns better than the Z224 shot (2003) which by the FAILED, as the bullet exited well below the throat wound level.
That Z190 approx frame coincides (imo) with Harold Norman’s description seeing the president with his right hand up trying to brush his hair when Norman heard the 1st shot. Then the president slumps as Norman describes. jFK slump leftward is maybe enough to theoretically have allowed a Z270 shot that only hit JC.
I have criticized your theory because of the lack of reactions by SS agents and only the Willis girl slowing down. But since I’ve given some logical reasons why Clint Hill may have missed hearing a 1st shot then I suppose it’s possible that Willis could be more sensitive to a 170 db rifle shot due to not having been desensitized to sudden loud noise of continuous motorcycle backfires as weed the SS agents.
Why would you assume Oswald fired the first shot in a sudden panic? He had ample time to study the layout. Why couldn't he have decided ahead of time, that he could probably get off a shot after the limo turned onto Elm and maybe 2 or 3 more after the limo cleared the tree. That first shot was the most difficult one but he had a better chance of scoring a hit than if he didn't take that shot.
He could have had the same mindset of hockey or soccer players. They know that the more shots on goal you take, the greater your chances of getting one past the goalie. Even if he missed that first shot, he would still have the chance to take the later shots. I wouldn't second guess his choices given that he succeeded in what he was trying to do.