....a new barrel, which is probably the best choice for most projects, simply isn't desirable when the barrel in question isn't a standard item.. Preserving a complex profile, and saving original markings are sometimes the essence of the effort. Many here are not put off by a project whose motive is nostalgic more than utilitarian. I think there may be people drawn to exotic work just as there are folks drawn to exotic firearms.
I believe a significant problem with this thinking is that one ends up with a non standard caliber and modern rifling, along with a most likely hideous new stamp on the barrel. That concept might turn a classic or antique into a utilitarian piece? Lining isn't a bad idea at all, for some situations.