[Bleyseng]

So how much petal travel are you talking about? 3" seems like that is halfway to the floor to me, is that about right?
If that is right, I would guess something is wrong with the master cylinder like you suggest.
The difference I notice is that with the 19mm MC and stock good working brakes the petal was very near the top of the stroke. With the 320i calipers it is futher but not by much and nowhere near the halfway point.
Geoff