you have to plug the oil ways in the main bearing caps that would have feed the balance shafts.
also most vectra B's had balance shafts on the x20xev, the early ones and last mk3 cav's didn't so the parts from these can be used, sump baffle/gasket, sump and oil pick up tube.
another point is which end of the engine does the exhaust run as some xev's it went towards flywheel end and others went to timing end.
this was my x20xev using vectra b block but cav mk3 crank, you can see plugged main bearing caps no 2 and 3. i tapped the oilways out to M8 and used M8x 15mm screws with copper washers and thread sealant