Engine / Gearbox match

Hello, the BMM engine in my Octavia combi 4x4 estate has failed in a big way ( broken crankshaft)  The gearbox is a  serial KXU.  i'm looking for a replacement engine.  Are there other Skoda 1.9 or 2.0 litre diesel engines that will mate with my gearbox or am I restricted to another BMM engine?    Can anyone suggest a trustworthy source of replacement engines? Thanks