Yea- the only thing I can think of to try is with the vacuum gauge connected to the ported vacuum, lower the engine speed by turning down the idle set screw until the engine dies and watch the gauge to see if the vacuum drops off significantly at any point before the engine dies. But if I'm only 2 turns open to begin with, I'm not hopeful... Other than that I'd have to conclude that if I'm not getting proper vacuum from that port then my carb must be defective.
Is it possible that there was a design change with the Performer series at one time where they swapped ports? I know that's a long shot but it's the only remotely plausible explaination Tomorrow, for grins I'll check the vacuum on what the manual says is the 'full vacuum' port. MAYBE the manual's simply incorrect- but I seem to remember seeing several posts here confirming what the manual said....
Edit: In googling around in other non-Mopar forums on the question of Edelbrock ported vacuum, someone had mentioned that there were 2 types of distributors vacuum advances - one would advance with increase of vacuum, the other would advance with decrease of vacuum. I'm assuming Mopar distributors use the increase vacuum/increase advance setup. In that case the carb might be ok- but this particular model (1405) wasn't meant to work on Mopars? Personally I find that hard to believe, but it would explain what I'm seeing on the ported vacuum readings.
Tomorrow, for grins I'll check the vacuum on what the manual says is the 'full vacuum' port. MAYBE the manual's simply incorrect- but I seem to remember seeing several posts here confirming what the manual said.... 
