Yikes,
that's too bad. I had a similar experience with an old Record "SS" #4 that i got on the bay. Pieces of the cheek on mine had actually broken off during shipping. I decided not to return it, but to go ahead and fix it up as a user.
Cast iron can be welded, though i just brazed mine back together. It's easier to do with such thin pieces and is more than strong enough for this purpose. I ground out the edges of the break points to create a "v" gap when the pieces were put back together. There was also a crack in part of the cheek that didn't break off - i ground out a "v" notch along the crack to give the brazing more surface area to bond to. I clamped the pieces back together and fired up the torch. I laid in more bronze than was needed to fill the notches. Then, when it cooled back down, i ground it smooth with the surface of the cheek. There's a noticeable difference in color between the bronze and the iron - it's an obvious scar.
Ironically, despite it's "history", this plane is one i use most often. I put in a Hock aftermarket cutting iron. The two piece chip breaker is really nice as well. The ergonomics are great, and i really like the large depth adjustment wheel. It's no looker, but it's a fine workhorse.
If you were purchasing the plane strictly as a user, and the price was good, i might just braze the crack, clean it up, and tune it to perform well. If you were purchasing it as a collectable piece that you can use, or even a shelf ornament, i'd probably return it.
Paul Hubbman