Hi Marcus,
this code is actually 460U, that is, a paint code identical to what we show in the manual as 460 G.
I posted my question on Pagodentreff and fortunately a member there provided the answer:
"460 Zündkerzen für Touristen - USA ab 01.11.1962 bis 31.10.1968"
"Spark plugs for tourists" - makes sense since the car was bought through the European delivery program and was picked up in Germany. It also has code 663 "50 liters of fuel" to allow the new owner a few km to find a gas station.
{sorry, I forgot to send the tumbler wafers, they'll go out next week}