The Z Film was privately owned and under lock-n-key for 12 years. As evidence it is worthless.
The following week the most important key frames(besides the headshot) were published in LIFE magazine and allowing for production and distribution, the amount of time to alter these frames all of which can be perfectly slotted back into the original, was only a few days, and is simply was not enough time but don't believe me go and ask any older SFX specialist and ask them exactly what could be done with 8mm film or any film for that matter and then ask if your ideas are actually plausible.
Another problem for you is that all the individual elements that you think were edited all have their own specific properties as in lighting, motion blur, directional shadows and angles and etc, and if you cut something out and stick it somewhere else then it's a guarantee that the moved object will be out of place with the surroundings.



The following year The Warren Commission published
every single frame from Z171 though to Z334 and they are all the Full Frames that included the ghost images between the sprockets, they also included the graphic head shot.
And every frame is exactly what we saw published in Life Magazine a week later and up until what we see today.



JohnM