I'm not too worried about potential hg problems - if it fails, it fails and I'd get it sorted.
Do these cars have any particular rust issues?.
Also, at what kinda mileage do the clutches need replacing?, as if a potential purchase is near to clutch failure mileage, I could use it as a bargaining tool on the price?
For rust, the main issues tend to be the front subframe mounts and the underfloor coolant pipes - the latter if they haven't been replaced I would be tempted to so.
As for the clutch unless it have been abused I wouldn't expect it to need replacing at any time. However the arm that goes through the bell housing can size due to a lack of use and the clutch fluid isn't on the service schedule and if unchanged for a long time it can make the clutch feel like it is failing.