If you're looking for custom decals including white contact Ricky Rupp at Modern Rails Decals (modernrails.com). He's done a lot of custom work for me at very fair prices. If you can send him camera ready copy with the exact size you want the finished product it will reduce your costs somewhat. He did a whole set of New Haven coaches for me about 15 years ago, and other work since. The pics are out of focus, but the decals were perfect. I sent him copies of the script and N.H. lettering from a book along with the size i wanted in the finished product. Not only is his work great, but i think you'll be pleased with his prices.
