Stan z:
I'm sure no expert but I believe at least some Holley 4bbl carbs have the PVC port located on the side of the carb mounting flange under the vacuum secondary device. If I'm right, from your top photo, it looks like your carb may have a plug in that port. There are typically other ports (one is full vacuum and the other "ported" vacuum [for distributor advance]) located on the opposite side of the carb from where you're holding it. As far as the power brake booster is concerned, I believe it needs a continuous (not ported) vacuum source like where you're pointing in the second photo.
Like I said, not an expert by any means. I'll be interested to see what some of the other guys (who have forgotten more than I'll ever know) have to say on the subject.
Russ
