Most Engine Numbers are already out there , getting the mating number is a bit different
While he was bent over your engine, I hope you took the opportunity to rearrange his testicles with your boot.Totally agree that this is the saving grace!
Still, the first time I was on Bonneville Salt Flats racing my Black Lightning, 'someone' rubbed the salt off my freshly painted engine with his finger to see the mating numbers.
I have come to the conclusion that the more information/documentation there is on my bike the more difficult it will be to pass a fake version of it as the original.