George Washington' Hatchet.

Very true, Coke,
Whe I was doing dome cosmetic work on the UP's 1243 for the 1990 Wyoming-Idaho centennial train, I started looking at parts as well. I found the right cylinder was original (sleeved, though) and a few other small parts. The tender had been replaced with a Vandy, the Injector had been replaced with an inspirator, even the cab window had been rebuilt with a bay window. We had to have the number plate cast in 1989. But... It was still built in 1890.
In the 470's case, 70 years of maintenance can change a lot of parts. Hence my suggestion of a new boiler and cylinders on the old, but rebuilt running gear.
It's like George Washington's hatchet... It's had five new handles and three new heads, but it's still George Washington's Hatchet.
Rick Steele