There are lots of UK Coupes with mileage over 200,000.
From my own experience, the items to look out for are:-
Hot oil pressure - anything above 1.5 bar would be good at that mileage.
Compression (hot) anything above 150psi would be good, but you should be more concerned it's the differences across the cylinders. You should be looking for a maximum of about five psi difference
Valve guides can wear, leading to smoke when on a trailing throttle
If the engine feels smooth and runs well, there's no reason not to buy it. History is important though - I would rather buy a high-mileage engine with a lot of history than a low-mileage engine with gaps in the history