G. H.W Bush was working in the oil biz and thinking about what it would be like to be elected to the House of Representatives in 1967
That’s 4 years after the assassination.
I don't think there's anything to the theories, but the name George Bush does turn up twice in the files.
Once is in reference to a CIA agent the FBI briefed about the assassination. It was probably another George W. Bush who worked for the CIA at the time, but he says he wasn't briefed.
The other reference is to a George H.W. Bush who called in on the day of the assassination to say that he had heard someone making threats to kill Kennedy when he came to Houston.
Apparently, that was the future president. I think the conclusion is that Bush had nothing to do with the assassination, but the guy who worked for the CIA and says he wasn't briefed is one reason these theories are circulating.