The engine that's on it came out around 1957 and the recoil starter looks like a Fairbanks Morse that puts it before the mid-1960s.
My Tecumseh manual that gives cross-reference numbers does not even show your specific engine #. Looks like 143.50010? My Tecumseh dealer book shows . . . Craftsman 4 horse vertical engines as 143.50040, 143.50045, 143.54500, and 143.54502. Engines will be Tecumseh V40, V40B, VX40A, VX40B, and VCX40B.
I've probably got around 50 riders of the same vintage. They tend to bring $75-$100 at auction.