I had one of those a few years back. A very enjoyable cartridge to shoot in that rifle. Most people are way more interested in the .45-70 than the .38-56. You should be able to find a few 1886's in .45-70 listed online. Probably about $500 less than a .45-70 with a round barrel. The octagonal barreled ones will be priced higher. The bore being pristine is very good though. Mine was quite pitted.
Chris.