Bob, that’s assuming there actually IS still an original around to be restored.
How many historically significant models are there that simply do not exists because every last one was scrapped? That was the primary driver behind the British Peppercorn project (that and that someone discovered the full original planset carelessly tossed away in a disposal skip)
I can think of a few steam loco’s I would love to see returned to active duty, the Pennsy T-1 for example, but since every last one of them was scrapped, the Peppercorn option is only hope for that ever to happen.
I would really love to see the monster 3 cylinder 4-12-2 Union Pacific 9000 at the Fairplex reborn, but its probably so far gone internally and its boiler too eroded that it will never happen. The shear costs would be so prohibitive. Its the ONLY one of its class left in the US out of 88 built. The Hudson they have at the Museum would be a better candidate. If I ever have the money in epic amount though I would shoehorn possession of the SP 3025 4-4-2 Atlantic currently at the LA Traveltown site away from the city to be restored, there’s almost no Atlantic’s operational left. Its small enough to manageable almost anywhere, and not so big as to require special handling or pay the piper like what happened to UP 844 at Sacramento a couple years ago.