For the most part, what Killeratrod said is true. There are a couple exceptions. I wouldn't recommend a chromed carb. The "pot" metal will expand and contract so much, the plating will "loosen" over time. Chrome "flakes" in the fuel path can't be good. Most of the REALLY "shiny" carbs you see are not chromed, but polished aluminum.
The other is the oil pan. I know, I too have seen MANY engines with chrome oil pans. I've never been comfortable with that. The chrome can reflect the heat and while not "drawing" heat, it can "retain" it in the oil, definitely a bad thing. I've also found chrome sheet metal to be more apt to leak than "natural" or painted metal.