Rattle can petty blue
As a pinstriper, when I needed a bright blue for my 340 I mixed in up in leaded 1-Shot and brushed it on and it lasted 20 years til some moron mechanic decided it wasn't the correct Mopar blue and rattle canned it over, boy was I pissed and took care of him in a hurry where it hurt, in his pocket.
Engines don't need hi temp paints and just needs real paint which probably isn't available any longer due to the EPA and its battle with anything that lasts, like leaded paints and I am fortunate to have a lifetime supply for my trade