Everything in your write-up looks fine to me.
I too have a model 'N' but a smaller 9x34 dating to roughly 1933. I've owned mine now for 4 years and it's my go-to lathe for smaller work.
My 9" has a heavier built headstock compared to other 9" South Bends of the same era. The bed is also wider and has the same cross section as my ~1944 Heavy 10. It also has the similar heavy double walled apron and the cross feed and compound both have adjustable tapered gibs. My research indicates that Model 'N's were the more expensive commercial line lathes. During the Great Depression South Bend cut out some of those more expensive features to reduce the cost in some of their other lines.
My 9" sat unused for many decades and shows little wear. Although the controls are slightly different, in practice they work similar to the Heavy 10. Given how overbuilt it is, I expect it will outlive me by many years.
Just for interest's sake, my Heavy 10 is also an unusual model, a Series 'S' benchtop model. It's labelled as a 10L 487Z and has the large bore spindle. However, it has the typical SB rear countershaft not an undermount drive. The lathe is illustrated in the 1941 South Bend catalog on page 41 along with the 487Z catalog number.