Flintfan,
I suspect Redman can help you. Failing that, if you look in the back of "Rifle"magazine, in the adverts.,you should find a couple outfits that can do this work.A 38 S&W Special barrel could be "short chambered" to .360#5, or a .312-.313" barrel could be chambered to 32 S&W long,for a good version of .320.
Mike