Back when I was trying to decide what color to paint my engine, came across an article where it was found that black paint rejects heat better than other colors, which was why the automakers were using black in the 2000s. I painted my engine black, and found that I was unable to locate a bad oil leak because I couldn't locate where the oil was coming out. I could only find where it was coming off the bottom. Incidentally, this engine was built very poorly by Hunt Engine in Fort Smith AR, and I even took it to the dealer (after a month of not getting anywhere with it) whose mechanic advised that the rebuilder had put incorrect bolts in all over, amongst other things. When I pulled it and took it back to the engine builder to figure out what he screwed it, when it came back I said screw it, not going through that again and painted it Chevy orange (Chevy engine). I'm just glad that POS engine is out of my truck, and the new crate engine is sitting in its place. All I need to do is put the intake and accessories on it, and I'm on the road again!
In other words, I do not recommend black (or any other dark color for that matter) for an engine regardless of reason, because it's too hard to chase down leaks later on. Paint it red, paint it blue, paint it purple with pink polka dots, just don't paint it a dark color.