I sprayed out a few spray bombs recently trying to match color to my engine components and here are my observation. I tested MOPAR Performance, Dupli-Color and Plasti-Kote, comparing each to relatively protected pieces of my engine components as well as the six barrel air cleaner lid in various lighting conditions, lighting can really make a difference when trying to compare paint shades.

MOPAR Performance was a pretty good match to the engine components, but a bit dark to the air cleaner.
Duli-Color was my least favorite being darker than my engine components and much darker than the air cleaner.
Plasti-Kote was just a bit brighter than engine components but almost a perfect match to the air cleaner.

Of course should you change your mind most will swear by Frank Badalsons acrylic enamel to match the engine color, but you will need to spray this with a gun.

Since I have an AAR my plan is Badalsons paint for the motor and Plastic Kote for the air cleaner.