I had some White Magic on hand that my wife got when she went to visit relatives in Canada last year (I can only find it in Canada). I didn't specify which grade to get, so she got me a bottle each of 40, 30, and 20. I was saving it for a colored phone, but thought I'd try it on a white phone.
I tried it on the receiver cap of my white AE 80 that I was preparing to treat with the home-brewed retrobrite. I coated it with the 40, put it in a dish in a cake pan and left my work lamp on it overnight. It seems to have worked pretty well, although I think I'll give it another dose. I don't have enough to do the entire phone, so I'm just going to use it on the receiver cap so I can compare with the home-brewed retrobrite on the rest of the phone.