Hy Iron Clad, I'm glad your brake booster passed the test, a lot of the old trucks I've been involved with experience a slight change in idle when the brake pedal is depressed, I'm not sure if it's actually a temporary leak in the system, or because of the distance the vacuum signals have to travel. At any rate if the booster passed the starting the engine with your foot on the brake pedal test it should be functioning as it should.
