Andreas. I wouldn't worry about the oil leak as others have said it's usually the sump gasket. Mine leaked and is dripping again. Cheap to fix. Clutch, is only a price problem when it needs renewing as it's an engine out job. There are mods you can do retrospectively to ensure the next time it can be replaced without engine removal. Hopefully it's the fluid and/or cylinder. Mine used to get hard to depress after little use over the winter, but would free up with lubrication.
The 1980 is carbs, no ECU and no cats. The 1988 will be ECU and I am not sure if it needed to have Cats to be Swiss compliant. I am assuming the 1980 is already Swiss registered and compliant. I find carb cars much easier to work on . Others will comment I am sure but I am aware that electronics on 1984 plus cars were an issue. The big issue for me would be the state of the chassis and woodwork. 1980 +8s ash frame wasn't cuprinoled and mine deteriorated rapidly having been used in the wet through the 1980s. Wood work now long since replaced. Chassis on both should be checked carefully. Also check out the edges of the wings. There was metal beading around the inside edges of the wings and mine also an ali car originally got bad catalytic corrosion between the two metals particularly on the rear wing edges.
Hope this helps.
Stephen
