As usual, MG knows his stuff!
With the bronze properly tinned, the white metal will make a permanent bond.
What I didn't mention previously was that I had to remove the bush after line boring, remove the white metal and re pour it, because the crankshaft was tight to turn in places.
So, the first time the machining was done in a vertical borer. The LH crankcase half was bolted to my fixture, and the machinint clocked OFF THE CRANKCASE JOINTING FACE. After machining, the alignment was not perfect, because rotation was not easy.
I removed and repoured the bearing (as mentioned above), and insisted that the machinist set up off the LH (roller) bearing surface.
He then did the machining in a lathe, as mentioned at the strt, with perfect results.
This confirms what I have suspected for a long time; that the factory line boring of the crank case halves is not always at 90 degrees to the mating surfaces.
Richard