I guess it might be nice to lift the heads and have a look at the cylinder bores to check for scoring / damage etc. Could check the heads as well.
I've no idea how much work is involved in doing this, but wouldn't have thought that it was too much, given its a small 4 cylinder. . .
I think the ideal result would be to push for this option, or for them to agree to liability in the case that engine problems occur in the next X k's. Whether you can convince them of this is another matter (I don't think its likely).
But I would call the NRMA (if your a member) for their recommendations, or perhaps consumer affairs to see where you stand.
But you could try talking to them first - you never know what might happen, and then you don't have to go postal on their asses !