Engine pics look the same. Most likely the previous owner/seller didn't know what it was. The VIN says it is a 400.
BIG difference between a 400 of that vintage (which most likely has a 2-barrel carb), and a 460...... ........................................................... EDIT: Not as big a difference as I would have thought...... Looked up the specs..... 2-barrel 400: 170 hp / 330 ft-lbs torque 4-barrel 460: 195 hp / 335 ft-lbs torque The 400 was standard in the Country Squire that year, while the lesser full-sized Ford wagons got the 351 standard.