I agree with the stripper idea. The key ingredient in it you're looking for is "methylene chloride" aka "dichloromethane" which will strip even industrial epoxies, urethanes, acrylics..... all paints that I know of. It doesn't work fast (a few days maybe) & it is KNOWN to cause cancer, so don't do this in closed garage... and wear thick, rubber "dishwashing" gloves.