simple script for resizing a selected image

hi everyone,

trying to find a faster way to proportionally resize the width of a selected image placed in a frame (the frame has specific dimensions, cannot use fit content etc). 

in my case: the frames have a 39mm width (height doesn't matter, it's relative). when i'm placing the image inside the frame, the image must have a 35mm width (with height proportionally resized).

i have to resize every placed image manually and i have thousands. it would really be a time saver for me to do this automatically by using a script. (i have macro keys on my keyboard/mouse so i can assign any shortcut to run this script).