The idea of taking a modern photo, cutting out the face and blending it into an antique photo is the premise of Old Booth.
However, it isn’t in any way an original idea because AbsoluteVintage, another app on the Mac Store, does exactly the same thing in exactly the same way.
OldBooth has vintage photos for the 20s, 80s and a couple of Christmas ones. There’s quite a few, though some placeholders for the photos were actually empty. Having selected a photo, or mask, you can then load in your modern-day photo. These are quite likely to be hi-res so will need scaling which actually performs a crop. You can also use the iMac camera.
Once into the old photo, the new element can be rotated and scaled again to fit. There are also controls for photo brightness and contrast and the same again for the mask. The new photo is automatically converted to a sepia tone. Completed images can be posted to Facebook, Flickr and Twitter or saved.