I doubt it would be all that hard. If uou are working with a tight budget, drop your frontend and measure the fork strm very carefully, then go shopping at the bike swapmeets. There are 2 sorts of factory HD springers readily available for the 45 and big twin, and 2 sizes and 3 styles Indian Girders for the Scout and Chief that are not so plentiful, but you see them once in a while. There is a decent chance one of these may fit without too much trouble. Avoid the Indian forks with the 1/4 eliptical spring, those would be hard to adapt and put wierd stresses on a frame that isn't designed for it.
If you find something with a stem that is the right length but a different diameter, check with your local equivalent of the Breaing Mart. They may have a bearing set that will make up the difference.
Another thing worth considering, the stock forks with the shrouds removed and the gaters from newspeedmaster.com have a destinctively late 40's Triumph look.
