Very impressive building skills you have and it shows with everything you have done on this truck.
As for the engine color with a truck like this, I would paint it to blend in with the body.
I love the hot rod/custom trucks myself.
I've built two myself and will build more of them.
And theres a lot of custom show trucks with color matching engines and transmissions also.
Even working show trucks match sometimes.
This truck to me if I was building it would be built as a custom show truck,only driven to the shows,even if it has a trailer for it to match the truck.