All factory stampings started with a star the an A or AA (except for foreign made blocks) followed by a number and ending with a star. Over the years many engines have had their stampings filed down and re-stamped with something different that a factory number. This could have been done because an engine rebuilder stamped the engine with a "rebuilt" number. Or other reasons. Most of the time the original stamping was filed down. If you look at the pad you should see a flat smooth surface. The original surface was rough like the rest of the block surface.
Bob