Welcome CP30.
Wow, quite the machine. I'm guessing that you are talking about something like
http://needlebar.org/cm/displayimage.php?pid=3372 (you can link to picture, just not post the picture you got from somewhere else or you
can post a picture of your own machine)
I'm not very familiar with industrial machines. If you found the part number via
http://parts.singerco.com/IPpartCharts/
congratulations are in order. From what I could make out, it looks similar to a 9W or D9. I'm guessing you have figured out that Singer took over Wheeler & Wilson about 1905 and continued making machine that were essentially Wheeler and Wilson machines. There is a group for W&W machines at
https://groups.io/g/Wheeler_and_Wilson-Sewing-Machines but seem to be focused on domestic machines. I know there are a few members here and there. Maybe someone more familiar with industrial W&W is there but not here. It probably wouldn't hurt to try.
I have a Junker & Ruh model R, probably from the 1920s that has similarities to both the W&W 8 and 9 so had to look at both to figure out how to thread. I can't find parts numbers for the W&W 9 so can't verify that would work.
Janey - Neat people never make the exciting discoveries I do.