It was the "O" in the third character that caught my attention.
We have a number of things going on in the pictures you provided.
First the alignment and second the choice of fonts/stamps
Since all of the letters and numbers are well aligned as far as individually vertically and horizontally I believe they were not individually stamped but the holder allow for alignment between the individual letters to not line up horizontally in a gang stamp/holder. The apparent equal depths across the letters and numbers from top to bottom and left to right IMHO suggests that a machine was used to press them into the metal rather than being stamped by striking them by hand
As far as your top picture and the odd first O in your top picture is unusual and looking through the pictures I have I could not find another example with the round style for the "O". Is the the date on that carb later - service replacement possibly?