Are you sure the motore is wrecked? A load of steam out the motor or out the back could be "just" a head gasket failed, so not too severe... still a few hundred quids though.
Oily black smoke and a stench of smokey bacon, oil all over the floor might be more terminal ... but a seconda-mano engine would be fairly easy to find (£300 it says up there ^ plus a few hours to fit).
Ralf S.