Well, there has been some dabate about this very subject. The engine in the kit is a 8V92N, so the entire engine should be Detroit Diesel Alpine Green. If you do add a turbine, the engine should be silver. The one shown is for a 8V71, but it could be modified. The starter could be either green or black, filters would probably be white, fan would be green, altinator should be flat aluminum, air compressor either green or black.
Might I recommend these for a little extra detail.