Bob, in person in may seem a hair bit darker but I think that picture is representative-that is 25+ yr old Bill Hirsch paint and 50+ yr old Ford paint. It is pretty close. I always thought my factory paint batch is a little darker then typical. BTW that manifold is aluminum.
IMO from personal experience painting bare aluminum vs bare steel will yield a lighter shade for certain, which may explain the difference we are seeing. I used primer on all my engine parts as a baseline. However, here was a noticeable difference also on my unpainted bell housing as I couldn't to primer it.