All good points! I don't intend to do much detailing, in fact I originally wasn't going to do any. Here's how I plan to approach it:
1. I will duplicate markings that I do find, after photographing them. No brainer.
2. I will not do any Markal/crayon markings that I do not find. That would be faking/fabricating for no purpose. My car is undercoated, so unless I remove that, I won't have the shift markings on the outside of the front frame rails.
3. I might add a VERY limited number of paint markings for things like torqued nuts, if I can find reason to believe that "all" cars from that timeframe/factory had them. I'm not making a show car nor making a sale, so I don't have motivation to fake a painted pony. This would include getting opinions from yourself and Charles and other experienced folk.