Eleeton,
Even though this is a crying shame, thank you for sharing your experiences. It helps steer others away from teh same mistake. If you went on what is on Mr. White's website, you wouldn;t think something like that to happen. All looks good on there.
I am having a 20g. SxS rifled slug gun built right now by a very experienced builder in the midwest. Oddly enough, in my search for a builder, I actually did stumble upon J. White's information and did place a call to him to talk about a conversion. I never got a return call. Good thing I guess.