Yeah, I learned that lesson too, also the hard way. I didn't know a clay bar would remove the overspray so I used the power buffer and managed to cut the color off on two edges where the paint was apparently already thin from 34 years of waxing, etc. I was disgusted with myself to say the least.
My goal was to just drive the car for the first 5 years, then embark on an engine rebuild and repaint. However, as I do maintenance work such as replacing a radiator, I go a bit overboard so I don't have to revisit this section later.
Anyway, thanks for the tip. I wish I knew this last summer when I did it. Thanks!