Not that it has anything to do with the OP's question...but later in a car's career, an engine could have been painted just about any color.
For instance, Jasper used a light green on just about everything they rebuilt in the mid-late '70s IIRC (I put one of their 327/ 365horse SB Chebbies in a Stag in about '77).
Many local rebuilders just painted everything black, many engines got painted light colors to make leak spotting easier, etc.
Just a thought, in case you're building a non-creampuff.