Jake, I hope you build a Road Tractor. And I hope you share your experience with the rest of us as you do. I, for one, am very much interested in 51-53 Road Tractors myself and have much to learn about them. The knowledge, experience and advice that comes out of this site is second to none. I'm not one of the guys that can help you much. I'm a new guy like you, but my truck, I think, started out as a 53 Road Tractor and I'd love to take it back to being one. Good luck on your journey. I do have to say though that 55 mph is probably not going to happen. Mine is working hard at 45. If you want 55 you'll probably have to pull the chassis and put some modern version in its place. Then it'll start and go and stop and all the things modern trucks do, but unfortunately it will no longer be an old truck. It'll just look like one from a distance.
Geo