There is definitely 3 reds at least. The orange-red on X2-186S and Chevs is X2 red I think, and the red used on other engines from HK on is Holden rocketred from memory. I'll see if I can find paint formulas.
Here is a bit of info although not all of it is correct:
http://holdenpaedia.oldholden.com/Engines_by_Colour
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