Which lens for 0.625 magnification when reversed?

I am setting up a rig to photograph slides and negatives. Using a Canon 1.6 crop body I need to achieve around 0.625 magnification to get a 35mm slide to fill the frame.

Just looking at a few ways to do it and it seems that a reversing ring is the simplest and cheapest method to achieve this.

Question - Can anyone suggest a Canon lens that will offer around my required magnification when reversed?