I thought that license plate looked familiar. I saw 4915 in person a couple days ago! It was up on the rack next to 559, both at DPI. You can see it in the background of this picture I took:
IMG_7572.jpg
(559's in the foreground and 4915 is one or two wheels behind 559).
Anyways, since you're asking about blue, I'm not sure if this would help any, but
here's a picture of the "stock" coloring to the SPEC engines, most noticeable on the timing chain cover next to the wheels. That is, if you went with the "paint the engine the same color as it is without paint" powdercoating like I did. The pictured parts are fresh back from the powdercoat shop. Maybe this might help you match colors better.
I think as long as you don't pick too many colors under the louvers, you should be fine. I did a quick search for "Mopar Engine Compartment" on Google Images and came up with something that might help. Take a look
here; the fourth result shows some blue spark plug wires and might help you get an idea of what it'll look like!