I'm rebuilding my '67 273 mostly to factory spec. the 1 thing I can't seem to find is: Were the exhaust manifolds painted from the factory or kept their cast iron finish without paint? If painted, what color?
If you do decide to paint them use POR15 manifold grey. Works awesome, brush able and can be touched up by brush if need be. Seal the can with a layer of saran wrap to help keep air out.
It has the texture of thin valve grinding compound. This is the 2nd set I've painted out of this can. High Temp