Welcome to the challenge Rock. Nothing more challenging about PSing a figure into a film still than older movies. You always run into poor picture quality, bad coloration, lots of little challenges that you really have to play with to try and blend with, especially the better your camera because you end up with a crisp, well colored shot and essentially have to make it look like ^^^^ to fit in with the frame. Blur filters can help you, play around with the program, have fun.