Barry Jensen of Bits of Pieces in Delta, BC re-barrelled a Smith for me. He didn't replace the barrel with a Smith barrel, but I'm sure he could do so. The problem is getting the barrels. Barrels are one of those gun-related things that the US won't allow to be exported without difficult and expensive licensing, and even then the restrictions surrounding such an export make the whole thing practically impossible.
It might be necessary to ask Barry or a similarly competent 'smith to manufacture a new Smith barrel. It's expensive and time-consuming. It's hard to see where it would be advantageous to have it done.