I have used the POR-15 exhaust manifold paint on several sets over the years and I've been happy with it. I sand blasted the manifolds, cleaned them with a rag soaked in metal cleaner, then baked them for about 15 minutes at 350 degrees to burn off the metal cleaner, then brushed them with the POR-15.
I did this on my '62 409 back in 2001 and they still look very good. I just did the set on my Nova, picture attached. The paint is a little darker looking than the VHT cast iron paint, but it sure looks in my opinion.
