Like what has been said, buy on the body, not the engine. They can be pulled out of metros for cheap as hell. How many miles does your missus do in a day and on what kind of road? If theres motorway work then you may want to consider a later MPI model with a 2.7fd though these also rust quicker than the earlier models. The radiator set-up means that the engine bay is well ventilated but I have seen a few that have overheating problems in traffic and 1/4 but never encountered the same problem in mine. Other than that, get yourself onto
www.theminiforum.co.uk, buy one and get yourself to the IMM in brum this year.