So even in the statements you quote, McClelland said "I could see, of course, all the extent of the wound."
Evasive and diversionary. But true to form.
Again, how can McClelland be "looking down" into a gaping wound at the back of the head if he's "standing just above it" such that he could see it "extended down into the head"? The President's head would have to be turned so that the back of the head was upright.
"That there was not only a horrible gaping wound but that it was
a cavity that extended down into the head. And as I stood there
holding the retractor, I was looking down into it all the time. I was
no more than eighteen inches away from the wound all the time,
standing just above it, which was ten to fifteen minutes at least."
-- Robert McClelland, 1991
And, if he's taking about the "rear", it must be the mostly on the right side.
"He was in terrible shape; the right side of his brain had been
blown out."
-- Robert McClelland, 1993