Explain the bullets hole in the windshield then
I say 90% because Bugliosi did not address any of the details of a book called appointment in Dallas by Hugh MacDonald (a man with stellar credentials). I would have liked to hear an argument against his presentation.
Regarding the specifics of your question. I will admit that the "bullet ole in the windshield" is a new one to me. That lowers that 90% certainty and It is something I will look into in the future.
I'd start with Bugliosi's book, but I do not have access to it currently. Thanks for brining it to my attention.