Morris Minor Owners Club

Is there any reason not to tee-off a vacuum gauge pipe from the same vacuum advance pipe drilling on the body of, in this case, a HIF38?

I would suggest that you will get a better indication of the manifold depression/vacuum if the take off is directly from the inlet manifold.
You may not get get a indication of the correct degree of depression/vacuum in the manifold as the vacuum take off at the carb is basically in the wrong place for a gauge.

Thanks Phil, problem is that inlet manifold is steel tube courtesy of Manifold and although they provide a servo take off steel welded stub there is nothing for a gauge.

Correction Maniflow

No problem - drill and tap the Maniflow manifold to suit the vacuum gauge take off. Better still once fitted braze the adapter in place.