Stamping of numbers is required in some countries for licensing and registration purposes. That may be the case here given what he has already disclosed
chrint is this the reason for your stamping or is it to make the car appear more original? If your stamping for registration purposes you might want it to not look original so your not going to mislead anyone else into thinking its original but instead it may be seen for what it is, just fulfilling state law
As for paint markings I think it's best if you start a new thread in the 69-70 section for that question. Keeps things easier for others to find information when they use the search and keeps things a bit more tidy that way
Will need to know when the car was built and the body type
Thanks