i don`t mean to sound stupid here,but i know what grounding of an engine number entails.
there will be swirl marks left behind,mine has none.it is pitted as is the rest of the engine from the cast process,the picture shows it shiny but what with the camera flash and me cleaning only that area it would do.

can you really stamp your own number?

would it be worth contacting ford with the chassis/build number ?
dave