Experimental work.

To edit the picture, I used the first image as the background and layered the second on top. I added the vector mask, and lowered the opacity of the second image so that I could see where to place the head on the first image.
After doing this I used the brush tool to erase the parts of the second image I didn't in the final image.
I then changed the opacity of the second image to 100% and flattened the image.


Result.