That too could be open to speculation Bob especially to an unknowing person in the market looking to make a purchase. Not saying that is your intention. Honestly these are visual changes to the car so why the need to add a code that few could read on the fly anyway? Create a portfolio both photo and written of the work you have done to the car. it will bring more attention to your details of the car than an E55 etc code.
in my case,I`d like to have a feder tag supporting what I`ve done to the car on it,which wasn`t even an option in 68, so there`d be no fraud possible--------bob