Frame off is a generic term, so it really depends if you are doing an original restoration or not.
Yes, on our original restos, we reproduce engine inspection stamps, grease pencil marks on the bell housing, body mount location shim numbers, correct window etching, etc.
For a modified Bronco, I would not bother with it.
Here are a few pics of some of the original marks we have reproduced and a few of the reproductions we did on a couple of our projects.
We also later put the grease pencil "OK" on the bell housing shown and also did the marks on the frame at each body mount that indicated the amount of shim on the assembly line ("0", 1/16" etc) that were all visible when we tore it down.
IMO, it costs next to nothing for the grease pencil marks and if done correctly on and original restoration, looks cool and adds to the authenticity. The custom stamps and stencils we have had made can cost a little, but are worth it to us when we are doing our restorations that will be judged. We currently have done two AACA Grand National award Broncos (the first two Broncos to receive that level) and our latest will likely get its Senior award next month, and hopefully its Grand National next year when it is eligible.
IMO, when doing a full blown restoration, it is the attention to small details like these marks (and many details) that sets one restoration apart from many others where that level of detail was ignored. It becomes often pretty apparent when you see vehicles restored to various levels next to each other at shows.