I cheat, I have the print catalogue.
I got the Colt diameters off a gunboard that Bing turned up. Nobody cared what an Anaconda barrel measured. The gun prices are so escalated, nobody is working on them anyhow.
There are Smolt/Smython conversions out there with a .562x32 Colt barrel taken down to K frame .540x36. I am told that there is some amount of old thread showing and the shop just kind of cross threads over it. If so, it won't be pretty and you might not be able to get it back apart, but they shoot.
I have seen Smythons on N frames. Looks like you would have to make a bushing for that.
Apparently a late model (one front sight pin) Python barrel should go right into a L Smith.