I did a repaint and lettered a set of Williams heavyweights in Frisco Firefly scheme along with using the Doric steam engine and tender trim on a Lionel Frisco Mikado. I got what was the last of these from that old decal company that went out of business. The one with the little envelopes. The name escapes me.. The lettering is gold in Railroad Roman font. I may have some remnants if you are interested. I am sure your work is much better than mine, I made the set to remind me of my experiences with the Frisco1522 and the memory of my brother in law who was on the 1522 crew.
Best of wishes on your project.