I would look for a commercial decal vendor. For a few decals, the cost is small and you can have white decals where needed and appropriate heralds you could never make yourself. I have made my own decals at times, and have been very happy with them, but finding a few Milwaukee F7 decals made the whole project of upgrading that fleet worthwhile.
It takes an iron man to play with a toy iron horse.
Here's a few photos of the GP30 I painted and decaled.
I had fun with this project! I think your E units will come out fine as well.
Hornblower
I have on preorder the undecorated Paragon 4 BLI E8 a/b units arriving next summer. I want to get them custom painted and decaled in the 50s/60s Illinois Central brown/orange scheme. I've been checking online for vendors who do this, and one in Arizona comes highly recommended. However several emails to him in the last 3 weeks have gone unreturned. So I wonder, despite the nice website and all, if he is still in business. I am in NorCal, can anyone recommend a reliable artisan to me? Thanks.
Ron