Superimposing 2 images of different scale and rotation

Hi All,

I am a researcher of ancient coins. Every ancient coin is hand made, and like snowflakes, no two are alike. However, much can be learned by tracing the minting process of these coins through an examination of the dies used to make them. So, I have to compare different coins to see whether they were minted using the same dies.

In order to do this I have to align two coin images on a Photoshop grid using two identifiable points that are visible on each coin. However, since I have collected these images from various coin collection sources, they are usually not of the same scale or rotation. So up until now, I have been putting two layers, each with one coin, on a white background with the grid showing, and slowing pulling the handles of the "transform" to get them aligned with each other and sized the same - exactly superimposed. Then I use the opacity function to check whether all the coin features line up, and they were made by the same die. However, this is very tedious! It takes dozens of nudges, pulls and rotations to get the two layers lined up exactly one atop the other. But, I have hundreds of coins to examine, and I have to find a better way!

My question is: Is there a way to simply "anchor" one point of the layer at a particular point on the background, and then "stretch" the other point to another point on the background while preserving the aspect ration of the layer? That way I can superimpose the two images in a snap!

I am attaching a Photoshop file of one such superimposition so that you can see what I am facing.

Many Thanks for any solutions or suggestions.

Haim