Maybe my online ID / handle gives me away. If looking for a .38-55 lever gun, I can't offer anything and have no comment. If considering a single shot, there are a plethora of .38 cal rifle barrels from which to choose. Green Mountain offers the popular Winchester High Wall profiles otherwise Krieger, Lilja, etc for barrel blanks.
Personally, I faced this decision sometime around 2005 or so and went with a very similar cartridge, the .38-50 Remington-Hepburn which is easily formed by blowing out .30-40 Krag cases. The NRA considers it a traditional, thus legal, cartridge for Black Powder Cartridge Rifle competition, as such there exists a vast catalog of bullet molds with which to cast depending on barrel twist, nose shape, etc.
If only due to differences in rim dimensions, never confuse .38-55 Winchester with .38-50 Remington-Hepburn. When available, Starline .38-55 brass is of very good, very consistent quality. I used it as the basis for forming .32-40 Winchester cases.
Good luck with your project.