Originally Ford used Ford Corporate blue for 69 351's
But you will read in other threads that not all Ford Corporate are not all equal nor look like the original color applied
IF you do a search you will even find a single page ad that Ford put in many magazines explaining the change and reasoning
By 69 you will normally find the year, plant and the sequential number used. They didn't care about the body type and they knew what engine it was - the number was stamped on it
All done by hand with individual letters so the application and tools were different from the ones used on the body. Uneven, some deep others struck lightly, upside down numbers - can be a collection of different details that affect what you see today