These are a far better carb than the Weber DCOE, they benefit by being designed 25 or so years later than the Weber, they were the last Hurrah of the performance carburettor before injection took completely over.
btw, they will bolt straight on to a Weber type manifold and the Dellorto 40 carbs are a direct replacement for the DCOE 45 series, giving equivalent power & better economy than the bigger Weber.