Hi John,
That screw looks like a replacement. At the time you plane was made the tote screw was a shaft with a brass nut on top. Hopefully someone didn't mess up the threads with the replacement screw. If it has the same threads, 12-20, as the frog screws or the front knob shaft it should be fine.
One additional question, if I may. Do any of you repaint the interior of the plane? Or do you leave it as is?
Yes, I prefer to have a fresh paint job on my planes when time allows. I have used mostly spray enamel. Home Depot used to have a black enamel spray paint for $1 a can. I haven't checked recently.
Other folks have painted them in their favorite colors. Most folks worry more about the usability value more than the collector value of these old planes.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)