The VIN plate on the dash MUST read 34467. If it doesn't, car isn't a 442 unless someone made a really good fake. You might find a different number on its underhood data plate; that discrepancy is well known and documented on 68-69 cars.
Look on the engine between intake manifold and water pump. A correct 1969 400ci engine will have a "G" cast into that area. To verify if car has the original engine, there's a machined pad at left front of the block, just beneath the cylinder head. 68-later Olds V8 engines have a VIN derivative stamped into the pad. If it matches the dash VIN, original engine. Joe Padavano has a good picture of this. Car should have "C" casting cylinder heads. If you find "D" castings on a numbers matching block you possibly have a W30.
442 will have boxed rear axle lower control arms and rear sway bar. These were optional on other Cutlass series.
Depending on the assembly plant the underhood data plate can tell you a lot. However if the car was built in the Fremont CA assembly plant the data plate has a lot of arcane numerical codes that are tied to the car's build sheet and job order. The other plants are easy to decode.
Others will be able to add more.