Whatever you do, it will be a killer piece. Maybe fade the wings to black at the tips so you don't need as much detail. There is a lot more detail in the wings than the train, and I think it confuses the design. Maybe tighten up the flames and pull them in closer like you said, might even say maybe the flames could be red and the wings teal. Man, maybe I am over thinking it now. I am sure you will make a cool tattoo.