When I go looking for cars, I always remind myself that in my experience, rust in the killer of older cars. Mechanical items (a gearbox, clutch, even an engine) can be replaced, I've got the bonus of doing all my work myself. The majority of times what kills these older Fords is rust. Rust is very much 'car cancer', so make sure that you check underneath and give it a good bang. You wouldn't want to replace the engine and spend £££££££ then come the MOT finding out it needs £300 worth of welding!
I hope you know what I mean mate, and hopefully there's some good advice here for ya