Ford has used more than two blues, even though most places just sell Ford "light" and "dark" blue.
Looking at my street car pics, it's definitely not Ford light blue, but it's also not the darkest Ford blue that Ford used either. It looks like the one in between, which was used on a lot of cars in the late 60s and 70s.
Here's an unmolested original survivor street car....
For comparison, this is Ford dark blue....
And this is Ford light blue....
And here is the Ford "medium blue".....
That picture was my own personal car, and it was very hard to find a place that sold the medium blue, but that sure looks like the blue on the street car engine above.