Garry - If you are happy with the 4BB1, then at least you have an engine, if (possibly) nothing else.  I have heard rumours about 4BB1s snapping cranks, however I am sure that won't be an issue in a land rover. 
Dougal posted here: 
Isuzu 4BD1 Bell-housings. - Cummins 4BT & Diesel Conversions Forums that all 4BXX bellhousing bolt patterns should be the same.
The only issue I can think of would be the legality of putting a 4BB1 in a vehicle as "new" as a 130.  But you could always convince the authorities it is a 4BE1...