Crankcase ventilation.
You can see the hard lines to the filter in this shot, that’s why he put the little riveted ring on the carb to clear them. You can also see how the RHD setup puts the brake servo quite a bit further from the vacuum port on the manifold. It looks like the carb is already on a 1/2” spacer so swapping that out for one with a vacuum port would be an option to keep the lines short
.
You can see the hard lines to the filter in this shot, that’s why he put the little riveted ring on the carb to clear them. You can also see how the RHD setup puts the brake servo quite a bit further from the vacuum port on the manifold. It looks like the carb is already on a 1/2” spacer so swapping that out for one with a vacuum port would be an option to keep the lines short
.