You definitely have to engrave, and it's in the NFA handbook.
The Form 1 is a request to make a Title I gun in to a Title II gun, and the handbook states, "The marking and identification requirements for a maker are the same as for a manufacturer. Refer to section 7.4 for a detailed discussion of the requirements".
The Form 1 is a request to make a Title I gun in to a Title II gun, and the handbook states, "The marking and identification requirements for a maker are the same as for a manufacturer. Refer to section 7.4 for a detailed discussion of the requirements".