Where in Michgan are you located? I'm just south of Flint, in NW Oakland county.
If you are close, I'd be glad to have a look at the parts and pieces of the stove you are getting from your sister. The biggest stumbling block will be missing pieces. Possible broken 'ears' for the interlocking of the cast pieces, and possible rusted-through cylinder of the stove body.
The main things that wear are the shaker grate system, the hinge pins on the doors, and any air dampers in the flue/ducts. Mica windows in the doors usually should be replaced, but may be in OK shape.
Some of these stoves are quite intricate, and some are quite simple. If you have an intricate shaker mechanism, you have to make sure all the gears, pivots, bearing racks, and grates are there.
I'd try to place all the pieces together, doing a 'dry assembly' of the stove, to assure that ALL the pieces are there. These stoves can be a real puzzle if you were not the person taking it apart.
You can get parts cast new, but if a piece is missing, you have to figure out what the piece looks like, make a working
pattern to make a mold from, then the part can be cast. I know where parts can be cast.
Take care, Greg L