Welcome to the forum Gene. The easiest way I can think of to do that is to make a jig that uses a piece that has two arms coming off it at the angle you want the dado to be. The piece of wood that the arms are sandwiched to has to be the same thickness as your rack sides. You'll use one side for the left side of the rack and the other side for the right side of the rack. In other words, they will be mirror images of each other. If you put a piece in between the arms that is the same width as the arms it will be easy to get them exactly the same. When you use them, work from left to right as you face the arm.
If that is confusing just say so and I will make a prototype and take a picture of it.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.