Manchuko? Gees, just spent a couple of weeks organizing a part of my collection. Moved it from Scott number organization to the CSS catalogue system, called Mengkiang in the CSS catalogue. Both are very different. I'm staying away from the MLO however. Have to say I got lost and confused more than once. And I still have some issues with what area is what area.
If you have questions, this is the place. One of our board moderators is writing a book on this area and is quite knowledgeable and the board admin is also very knowledgeable about all things north of the Great Wall.
Welcome and continued good luck