IMHO:
The boilers and frames are the same. Smoke box has either been modified or replaced, some details look correct, but not sure. Cylinders are the same and wheels with offset counterweights and crank pins were cast to accommodate the wider pistons. Of the suspension I can see, it all appears to be original for a K-27. The drivers and pilot wheels are new to the engine but I don't know about the rear wheels. It also appears that the axles may have been offset lower in new journals to raise the height of the loco.
Of the running gear. The main rods and side rods are new, as well as the cross head and arm. Not sure about the radius arm. The eccentric crank looks different but the eccentric rod looks the same. The combination lever looks the same as well, and possibly the union link.
The sand dome has been moved backwards to compensate for the additional dome. This front sand dome looks close enough that it could actually be 458's, the lid on the rear one looks like it could be 459's and 458's has been replaced. Most all the rest of the accesories have been replaced, like the bell, compressor, generator, cab, smoke box front, pilot beam, running boards etc...
The tender appears to be all new or from a donor engine.
Again, this is my opinion, and not necessarily fact!
Casey