I'm confused.

Is that picture of the pside balance shaft bore? IIRC, it is. The oil pump on a 2.6 is driven by the balance shaft chain. If a BS elim kit is used, both balance shafts get tossed and a very short spud shaft is bolted into the pump and a new short chain drives it off the crank sprocket, a large thin sprocket in front of the crank sprocket for the cam chain, which is larger, two row roller chain, not a small pedal bike sized chain for the BS, or in this case, oil pump.

There should also be a blank bearing shell in the dside BS bore to block the oil passage for that now missing shaft, without which you will have very low oil pressure.

The oil pump has a pressure relief valve under the large hex plug on the upper left of the pump. The valve is a spring resisted piston with oil pressure on the pump side. If the bore is scored, you lose a lot of oil pressure that way. The spring can be shimmed for higher pressure, too. I used a single flat washer under the spring. When the oil pressure exceeds the spring pressure, the piston uncovers a port in the side of the bore and the excess pressure is vented to the crankcase.

Also, tear the pump cover off and inspect the pump walls and gears for scoring and excess clearance, and that the chain sprocket was tight on the spud shaft. Clearances and measureing procedure are in the FSM on mitsubishilinks.com.