Alter some Images -- 2

I have 2 images below. An old image of a sad man and a padlock gate. My end objective for the project: have the image of the man on top of the poster with the padlock gate directly below- no white space between the two images. My problem: the pixels on both images get grainy and worse when making the images larger. Can you work on filling in the images to make them crisper as they get bigger please. I need these images (once combined into one) to fit on a 24inch by 36 inch poster. Presentation quality.