What is the best way to use guide lines to crop/zoom on multiple images to match
I have 4 images of horses that will be printed. I want that prints to match in terms alignment (ex: same size head, equal negative space around the horse's head, etc..)
I am using guides to manually mark where the top, bottom, left, & right side of the horse's head is located. Then manually adjusting the image so each horse is on the same guide lines.
If 1 horse's head is slightly smaller than the other 3, I need to enlarge the image so it fights on the guide lines. Currently, I am increasing the Image Size, then adjusting the Canvas Side to match the originally desired size (7500x7500).
Example of current (manual) process:

1) Is there a better way adjust the image size if I need to "zoom in" on one image (so the horse's head is touching the bottom & top lines)?
2) Is there a way to quickly add multiple guide lines to multiple images without having to manuall add and edit the location of each of them?
