I've read that too. I've also read that some 10,000 years ago the lion would have been looking directly at the rising of the constellation Leo at the spring equinox right before sunrise.
Judging from the overall size of the body, the head is proportianally smaller than it should be. And it makes sense that some narcassistic Pharoh came along and said my head would look better.
I have read that, too. However, that is how the thing has looked to me for a long time. As a piece of sculpture it appears to have fallen into inexpert hands. They didn't even blend the new head and neck into the old body, size disparity aside.
But, one thing might have forced them to do something: the muzzle of the original animal might have decayed and fallen off so they had to either clean it up or leave it a total ruin, which would have detracted from the fresh-built splendor of the Cheops pyrimid.