please help...340 casting numbers

If the car was built Sept 17-71 the engine should be dated prior to the car build date. Many blocks were cast a month or so earlier, warehoused, machined and possibly assembled, than may be warehoused before installation. 72's should have the VIN of the car stamped on a machined pad on the drivers deck surface in front of the cylinder head. the 25-72 (25th week of 1972) should be approximately June 15 of 72. that engine would make sense if the car was a 1973 that started production the first of August of 72