So this is a puzzling one… I’ve fully assembled both carbs. The fuel pump is sat considerably lower on the carb with the new parts.
I’ve compared the fuel pumps and they are identical. The difference in height can only come from the alignment of the cam. So it’s either the shape of the cam arm (they looked the same when offering the parts to each other) or the angle of the cam arm on the spindle.
The spindle came pre-drilled, as did one side of the cam. So the cam with the lower pump is at the stock alignment. I wonder if it’s a trick for those drilling there own spindle to make the fuel pump action more aggressive by drilling at a slight angle?
I suppose it’s possible there is such a thing as a performance cam. Bit of investigation required!