I’m afraid I know very little about paint / historic paint codes but for what it’s worth I’m planning on painting my Allard P1 fastback in a lighter silver colour and having taken some advice from a very knowledgable chap at Bailey Paints in Stroud, UK will probably choose the “White aluminium” from the RAL colour chart (see link below).
https://www.paintcolourchart.com/ral-colors/classic
It might be worth a call to Baileys for a chat, they’re super helpful and really know their stuff, they offered me a lot of useful advice on primers for steel vs aluminium for example.