[me and my metro]

The crank sensor actually attaches to the oil pump. The blocks are the same. The oil pan for the OBD2 engines are different for the sensor.
Just use all the stuff that is on your 96 engine. Match the oil pump gasket to the pump, there are a couple different gaskets overvthe years.
The heads are the same but there are no cam bearings so check your’s out carefully.
You are correct about the two ring pistons. I think they were splitting hair with that. The 95+ four cylinder stick is probably more available for the 3.8 ratio trans than finding an xfi original in good shape.