I doubt a different model Alfa would have the vacuum hose coming from the opposite side. More likely some knucklehead just installed the fitting in the wrong orientation.OK...I'll work on getting it out. I guess the used "donor" booster came off a different model alfa?
There was a BB discussion some time ago about the plunger length on the Vicks booster being too long. See: Brake Booster Adjustment? Dragging brakes and: Power brake boosterVicks had the ATEs for about 150ish last I checked...but if that used one in the box is any good will be going that route first.
An alternative to buying a new booster might be having your existing one rebuilt by Karps or Brake Materials & Parts. Although neither company's website mentions ATE, I would contact them before giving up on rebuilding. Of course, if your spare works OK, that would be a cheaper solution.
Yes, the pin that secures the pedal to the shaft can be a bear to get out. But you shouldn't have to disassemble that.I've heard of a pin or shaft that can break in the pedal cluster?