I'm sure you don't need me to warn that painting from paint codes, AND getting a good match
to your tank is fraught with difficulties. !
Paints mixed to code can vary wildly, particularly with different manufacturers and batches.
What could possibly go wrong ...
Best if you can get that tank over there, to ensure the shades of silver are at least in the same ballpark ?
Who knows, your tank may not have been done/redone to the EXACT silver that Douglas used.
??