It's pretty fitting that the #425 ended up sharing a shop with a Reading T1.
When Malcolm Oettinger rescued GM&O #425 from the wholesale scrapping at Paulsen Spence's Louisiana Eastern in 1962 (#425 was chosen over sister #426, also at the Louisiana Eastern, due to the #426 having thin flanges on her drivers), he really didn't have a solid plan of where he was going to operate a steam locomotive, he just knew that he wanted to operate a steam tourist line. He originally wanted the Reading Company's Perkiomen Branch but the Reading wasn't willing to sell that. Instead, they struck up a deal on two miles of the Pickering Valley branch, which had never been a rousing success for the Reading.
The #425 had not operated in several years, and to be certified for operation, it needed boiler work, including new flues. He ended up purchasing new, unused flues from the Reading intended for use in a T1, which had been laying around their main shops in Reading and installing them into the #425. So, yes, #425's rebirth as a tourist engine was over Reading rails and using Reading T1 parts.
Photos of the Valley Forge Scenic Railroad, as the operation was known, are incredibly rare, as it was fairly short-lived. The Pickering Valley Branch pretty much went from nowhere to nowhere, which was why the Reading had been willing to get rid of it. There hadn't been passenger service since 1934 after it made only $13.10 in seven months. It had also been largely dormant for years beforehand, and the locals were not happy about a steam locomotive suddenly running through their backyards again. There was immediate pushback from locals, which the Valley Forge Scenic fought back against, but they eventually lost when it was discovered that the Reading had filed for, and received, permission to abandon the branch a couple years before the sale. This meant that the land rights of the right of way reverted to the adjoining property owners, and the Valley Forge Scenic would either have to buy them out or get their permission to operate. That spelled the end of the Valley Forge Scenic Railroad, after six years of planning and two years of operating, and the #425, as well as the other locomotive that had been purchased for eventual operation, both went to the Wilmington & Western. The #425 never operated there, and sat until 1983, when Andy Muller purchased it and moved it to Temple to begin restoring it for operation on his Blue Mountain & Reading, which was the old PRR Blue Mountain Branch from Hamburg to Temple. Of course, the BM&R eventually became the Reading, Blue Mountain & Northern, and then the Reading & Northern (they barely even operate that original segment anymore either)