Good luck guy...the 500 number is either an error in the publication, or a botched numbering attempt by billings, the 1944 catalog lists #500 as a carbon steel set screw wrench (single ended) 3/16 size.
Could the 500 number be someone elses part # for the wrench?
That logo is rare , B&S overlaps Brown&Sharp, and I think there were issues, Billings stuff with even the plain B&S isn't common...(There are examples on AA, listed as a different wrench series...and not much else...)
Even as a C series wrench the 500 wouldn't match tho, as the C series seems to match more or less with the industry standard (early) numbers...
I think you hav a project - P