The lead will cause no problems with the finish. Lead was used before the invention of Plastic body filler (Bondo). You can just prime over it, you can sand it, just like filler.
And you don't have to worry about rust in those areas.
Frank
No better smell than that of fresh paint. I've been building and painting cars/trucks for 47 years. Not gonna stop now. http://www.coxcustomcars.com/
