Ford changed the actual location of the wound which had previously been established even by the autopsy diagram (among other sources) as being at the upper part of his back. Not at the nack of his neck.

The draft did not say "upper part of his back" either. Here are Ford's changes that he recommended:

http://www.jfklancer.com/docs.maps/ford1.gif

Not a simple "revision", as if it was done for insignificant reasons such as semantics or grammar.

The original wording in the draft was, "a point slightly above the shoulder and to the right of the spine." I don't think that wording is clear. Just what is "above the shoulder"? I picture something up on the neck. In fact, I think the final wording, "the base of the back of his neck," places the wound lower than what was in the draft.

When he altered the "wording", he clearly altered the evidence - the wound location is a critical detail of the evidence.

The Report included a copy of the autopsy report. That is the evidence, and that wasn't altered.