I thought the A-Series engines (4-cyl.) were painted what my Australian friends have affectionately called "hedgehog puke green". This has no metallic and is a darker olive green. If you're painting the engine yourself, do it in pieces as suggested. I was very pleased with the results I got using the THICK engine enamel from POR-15. This is not the urethane type coating used by POR for rust prevention, it's a very, very thick enamel for one or two coat coverage of blocks. Brush it on castings, spray it on things like valve covers. In spite of what they tell you, don't thin it with their solvent, use mineral spirits. When applying a second coat, do it while the first is still tacky or wait several days for the first coat to completely dry. I like their paint.
As for the fan, I thought this was a unique shade of yellow. If you're going for a nearly perfect match, you can go to Nissan and buy the screaming yellow they used on their 4WD trucks during the past few years.
Powder coat is great but to make it cost effective you'll need to assemble a large batch of parts to coat all at once. Yes, it's heated to fuse and flow out the particles, but I believe it's only a few hundred degrees. Warpage of formed parts will be minimal and the original shape should return without problems. Using it on a block would be very expensive because of its mass. You'd have to heat the whole block up to the paint's melting/flow temperature. That would be a lot of oven time.