I used Jim Carter's engine paint color. It's PPG ALK-200 and goes on with spray or brush very nicely. I found a couple spots on my engine with original paint and the color was almost exact.
I've seen a video advocating heating the iron with a propane torch to sweat out any oil, then prep with oil and grease remover. I'm not sure it's worth the effort however.
Craig's rattle can approach is the easy way out and would work well also.
