Vic,
I don't know where you are located, but the Waynesburg & Washington #4, a 3 ft. ga. 2-6-0, is still equipped with the Eames brake system. The engine is at the Greene County Historical Society, just outside Waynesburg, PA. The engine is locked in a shed, with screen wire doors, so you can see in, but to get up close to the muffler, you would need to have someone open it up for you. You would then also be able to figure out the control valves, piping, etc. It might be worth the trip down there.
If it is completely out of the question, a fellow discussion group member in Michigan, Ohio or western Pa. might be able to stop by on the way down to Cass in May, when they run their railfan's weekend. I don't know if I am going this year or not, but I think some friends probably are. It is only about a 20 minute detour off the route to Cass, plus whatever time it takes to get the photos and info you need.
Good luck,
Michael Allen