Timing /6 without advance port of the carb working correctly??

Impossible to tell where your advance port except by removing the carb. This what you're pointing at is just the external vacuum nipple. It's in the same place on all Carter BBS carbs; what differs is the placement of the inner end of the passage that nipple connects to: above or below the throttle plate at idle. Also note that if the throttle plate is not where it's supposed to be, the vacuum advance signal won't be timed/ported correctly. Reasons for improper throttle plate position include other wrong settings (fuel mixture and base spark advance set wrong = have to open the throttle plate further to get the right idle speed = vacuum port uncovered when it should be covered) or slop at the throttle shaft where it passes through the throttle body. There is no off-the-shelf/replaceable throttle bushing in any carb used as factory equipment on the Slant-6. If there's side slop in the throttle shaft-to-throttle-body junction, you need to have it rebushed by a suitably skilled machinist.

Also, the correct rubber bushing for the throttle lever (where the rod enters it) is available new from Gary Goers as part № 415 -- important to use that; a piece of hose or tape shoved in the throttle lever (as appears to be the case on your carb) is a common fix, but not a safe one. For details on Gary Goers see here (part № 415 is on page 18).

Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download.