I'm with John Walker. You should be able to easily sell the 923/02 gearbox and get enough money to properly repair your gearbox unless something catastrophic happened like a hole in the case.
If you are going to use the 923/02, in addition to the other things you are considering, you will need to cut a chunk out of the case for the DME trigger point on the 3.2l, unless you did the engine swap with carbs or MFI.
And the 923/02 is magnesium. That's why it looks magnesium.
