You have the correct generator and VR for the early 8N. You are reading the part list for the 8N wiring diagram in the F-04 manual, page 119 in my version, for the front-mount units to s/n 8N-263844. They say 'CUTOUT' but look at the picture and their #2 -it is a voltage regulator, not the cutout. Look on pages 48 & 49 at the 8N wiring schematic and diagram. It shows the VR and is listed correctly. You have the correct setup for your early 8N. The round can cutout, p/n 9N-10505-B was used beginning in early 1940 with the 9N-10000-B generator, at and after s/n 9N-12500. The Generator was a 1-wire/3-brush unit and had a 3rd Brush adjustment on the back panel. This setup was used on all 9N/2N production til the end. No 8N model ever used the cutout. The 8N used a new generator, 8N-10000, a 3-Wire/3-Brush unit, A circuit Design, at 11.5 AMPS with the new 8N-10505 Voltage Regulator. In April, 1950, at s/n 8N-263844, the side distributor was released, the generator moved to the LH side and was now a 3-Wire/2-Brush unit at 20 AMPs output. The VR also was changed to the 'B' unit. By the way, 3rd Brush gennys proved to be slight failures. The 3rd brush was meant to be increased when the lights were used so undercharging wasn't obtained. When lights were not in use, it was to be reduced back to the LOW setting. If the setting was left on HI, it would cause overcharging the battery. With the early 8N's, there was a Service Bulletin issued with instructions on how to convert a 3-Brush to a 2-Brush unit. So some units could still have the 3rd Brush adjustment screw on the back , but the internal wiring got changed for only a 2-Brush unit. You would have to look inside to see the config. The I&T F-04 manual has a test procedure to set the genny for correct output. I'd leave it to those settings and never muck with the 3rd Brush screw at all. If your wiring follows these diagrams. then you are correct. Also, if you are not experiencing any charging issues, the AMMETER reads about 3-10 amps when charging, and a slight NEG discharge or a ZERO reading when the lights are ON, you are good.
Tim *PloughNman* Daley(MI)