Even though Northlander and a couple others doesnt do smithing work, you could always buy it and take it to a local gunsmith to shorten and re-crown it for you. Most will only charge $30-40 to do that. Just to give ya a couple more ideas.

SSS and Sinman do not have barrels ready made to ship. They are like any other smith, you order the barrel and then they make it to your specs. So if you want one quick the the option above may before the quickest.