Although I am a fan of most C&O steamers, the few that come to mind are the T1, berkshire and the Alleghenys. Not only do I agree with Berkmeister...
Here is a picture of my grade that I made out of blue foam board. 2.6% accurate Grade.
Your Allegheny looks great! I hope you post more pics and videos of it. I am a huge fan of the H8 and being that the brass ones are hard to come...