Hi Arjan, I fix / restore / upgrade classic cars, so starting old engines after 30+ years all part of the job! I'd probably disconnect the fan belt, clean out the carburettor, clean the points, check or change the oil & 'give it a go' !! you might be surprised
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But only for less than a minute as you start to get things too hot. You'll probably have to change the raw water pump impellor, the water pump, alternator, fuel pump, rubber fuel pipes, points, condensor & battery, but worth a quick go first to see if it will go.