That was my first approach, cutting them off with a hacksaw. I'm a bit too ham-fisted for that.
I did see a video on Youtube where a guy did a rather detailed clip of how to remove them using a soldering iron and screwdriver. Actually quite a good video - stumbled upon it after posting this question.
I have a spare carb body, so I was thinking of giving this a try tomorrow morning on one of them. Otherwise I'm limited to essentially 2 1/2 turns out - fairly close, but 3 is typically better for the vacuum carbs from what I've experienced.