I had a similar situation on a ’53 25hp a couple years ago. My motor would be going along fine and all of a sudden it would quit just like it ran out of gas. I did the usual cleaning the fuel passages and a using a different fuel tank. Could not find anything wrong. I noticed my needle valve in the carb did not have the little wire thing that holds it to the float. I ordered a new needle and seat and my problem went away. Was it possible the needle was sticking to it’s seat? It runs fine now!
dale
