In cases like this, I wouldn’t take the image out to photoshop because unless you plan to clean up every frame that the subject is in, if he moves or talks it will be pretty apparent the skin isn’t matching right. Also, even if you do clean up every frame in photoshop, they need to look 100% identical or it will be spotted pretty quickly.
What I’ve done in the past is to use an adjustment layer in AE, add a gaussian blur to it , mask the adjustment layer and then add feathering to the mask. From there you can keyframe & adjust the mask shape as needed, do some motion tracking, apply the result to a null and then parent the adjustment layer to the null. Or most likely a combination of the two.
Here’s my result just applying a mask and blur to your image.

Johnny Cuevas, Editor
ThinkCK
“I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work.”
—THOMAS EDISON on inventing the light bulb.