I've  brazed up  the  crankshaft in  IH  balanced head/wobble box mowers with decent success..  Not near a long lasting  fix as the bronze eventually pounds out..  but it's never  'broke'..    But it was only to fix the small end of the spindle,   not both bearing registers like you show.  

Maybe just  getting just the beam if available.... then  transferring over the hubs?     Might be time to just write off a bad purchase.. it happens to everybody.