I would use any red that is close to the original shade. It will make the model look more protypical. I have some Walthers Ballast Hoppers that were lettered BN. I just painted over the letters and numbers in a similar shade ( Tuscan Red in this case) and applied new letters and numbers to make them into LIRR Ballast Hoppers.
I just bought the NYA 271 model also. Seems they made the mural
larger then the original and the "NYA" logos on the cab and nose
smaller then the real ones. I'll add a new horn,antenna, hoses and ditch lights to it. The trucks and fuel tank need to be slightly weathered also. Last winter I took one of my photos of 271 and photoshopped the photo. I worked on the mural and did some decal testing of it. That's as far as I got. Thanks Athearn, you made my life easier. See the results below.
3 Guys Hobbies in Smithtown has two of these #271 models in stock.