Working on tuning a 65 A code. It is nearly all original. I am looking for advice on how to test the vacuum. The only vacuum line I see is to the distributor, and its a hard line with what looks like a brake fitting. The spacer under the carb has no opening on the back since it has no PCV valve. I don't see another vacuum port on the 4100. Other than find a threaded line to cut and put a hose on it in place of the vacuum advance line, is there another way? I don't see how it was tested originally in my shop manual.