Hello, I am very new to the hobby. I just bought a Lionel 6-18001 (a rock island 4-8-4 with steam chest effect) and I would like to personalize it, first on the list is to replace the outer shell with one that has a larger firebox designed for a 6 wheel truck instead of a 4 wheel one, effectively turning the 4-8-4 into a 4-8-6. can anyone make such an shell? perhaps with a 3D printer? if so, it should be in Santa Fe colors with the engine number 7000.
Edit: I forgot to mention that the tender should also be repainted to Santa Fe colors, and, despite being larger than before, the finished product still needs to be able to navigate O-31 curves.