Atleast from the photo, that looks like refinish, so could have been milled off.
I've not found the casting number to be much help - to a carb guy who keeps track of such things, they might be a clue.
Keep looking. If it came from the factory without the choke horn, then the list number will be somewhere else.
If it was done later, most shops stamp or mark them, but a lot of folks don't.
Check the top of the metering blocks as well. The older factory metering blocks often have the carb list number stamped on them, sometimes in addition to the block number.
