Make sure that it’s a genuine car. Contact the Mini Cooper Register to check its provenance, etc. Unless it’s been the subject of a recent and well-documented restoration, expect to find some rust. Check the sills, floorpan, boot floor, inner wings, valances, door bottoms, headlight surrounds, subframes, everywhere in fact. A-posts are particularly difficult to repair. Fortunately, just about every panel is available, although some will need retro-modification.
Mechanically the Cooper is pretty durable and all parts are available. The A-series is a tried, tested, and trusted unit. But, it’s not immune to neglect. And it can crack between the valve seats (often causing a misfire). Do the usual checks for undue noise (especially top end), smoking exhaust and water in the oil. The gearbox, which shares its oil with…