Since no=one has responded, I will take a stab at what you have. Many States use the number that is stamped on the engine block as identification on the license. It looks like someone may have had a problem with there DMV where the id tag and license did not match. They probably redid the tag with the engine id to prevent further confusion and then you came along and tried to make sense of it all
I am not sure about the tag number being "ground off? It's a piece of thin metal that is stamped with number and letter dies. Is your tag screwed on or riveted on? in 1953 it would have been riveted on. Look closely, has it been re-stamped? Can you see any visible numbers in the background? Tag plates are available through some vintage vendors and this may have been a replacement tag.
