Decals look good, but I'm changing scales. Doing a 1/14 PC400LC-7. Dimensions are almost dead-on for model vs 1:1, and I think the model's proportions reflect the beefier look of the PC400. Oh well, we can make it pretty much what we want. Decals and a few specific added details will help the illusion and I have to go with what I've worked on and taught for the last 30 years.
I found a company that sells the powdercoat you mentioned. They also offer aerosol, brush and touch up paint markers for all the RAL color codes. It is
http://www.lowvolumepowder.com.
Ken