The question is not whether a jury would necessarily conclude that Oswald was guilty. By that standard, OJ Simpson and El Sayyid Nosair were not responsible for murder. We know they were.
What do you mean, "we"?
Juries can get hung up on an issue that they can't get past: like "did the gloves fit"? Some wingnut juror could get hung up on whether Oswald ever ordered a gun from Klein's and somehow convince themself that all the other evidence did not matter.
Your biases are showing. People who refuse to make the same leaps as you are "wingnuts"?
The questions are: 1. is there evidence on which a successful prosecution could be made that Oswald murdered of JFK? and 2. is there is any evidence that anyone else was involved in planning and/or carrying it out? The answers have to be: 1. Yes and 2. No. That is as far as anyone can go in this case.
You can't answer question 1 without it actually having been done. It's just a matter of conjecture how a trial would go. Yes, there have been a couple of mock trials, but they weren't all that authentic for various reasons. Question 2 is irrelevant to a finding of guilt or not for Oswald.
The issue that this thread raised, initially: "a scientific look at the Single Bullet Theory", was whether the SBT can withstand scientific scrutiny. In my view, it cannot. But that does not in any way change the overwhelming case against Oswald.
SBT or not, there just isn't an "overwhelming case against Oswald". It requires too many leaps of faith.