Mike, welcome to Oldgas...
IMO, your best bet is to go on Amazon or another 'Site that deals in "used Books" and pick up a copy of PCM's Guide to Gas Pump Restoration"; either 1st Edition or 2nd Edition...
In it you will find information on most American Oil Companies from the early 1900s to the 1970s... Included is sections on Sinclair ranging from 1916 to 1970... This information details if a Pump Plate or decal was used. And where on the Pump they would have been situated. For Pumps with Ad Glass and/or Globes; there are images showing which different logos were correct for the period of time... Etc....
