Body Work and Paint Estimate

The paint job is only going to be as durable as what's underneath it. On an "unknown" I would take it down to metal which can expose a multitude of previous sins. Personally, I wouldn't do one unless they wanted it stripped. Too much can go wrong when painting over a previous job where you don't know what was used. Uncatalyzed enamel or old lacquer paint, underlying adhesion issues, what have you. I couldn't guarantee it.