RW, I mentioned the vacuum again because, with the engine running and the booster vacuum line capped, I have at least some minor braking ability. As soon as I connect the vacuum to the intake manifold (again, with the engine running), the pedal goes limp and is completely bottomed out.

Since there is no way for the Booster to "leak" air into the M/C or brake lines, I figure there must be some connection....maybe not.