I will find the documentation where I got this and list it (it was factory documentation, Jack- I believe it was a service bulletin), but the 685 engine (161 F-head ) had:
blue block for low altitude export (below 5000 ft),
light gray block for high altitude export and low altitude domestic
yellow for high altitude domestic.
Cylinder heads were blue for low altitude export
black for high alt export and low alt domestic
yellow for high alt domestic.
Peripherals: Black for valve cover, starter, generator, air cleaner.
Natural metal: distributor, carburetor, exhaust manifold.
Engine color: timing cover, oil pan, bell housing, crankshaft pulley, harmonic balancer.
There was no orange block F-head engine. Where did you get your info?