Important: Do not allow dirt or debris to enter the oil pump assembly, cap ends as necessary.
The oil pan must be removed to access that pickup tube from the oil pump.
Oil Pump, Screen, and Crankshaft Oil Deflector Replacement Removal Procedure
Have you removed the oil pan yet?
Here is what GM says to replace the timing chain and gears.
Engine Front Cover Replacement
J 41476 Front and Rear Cover Alignment (at crankshaft seal area)
Important: Align the tapered legs of the tool with the machined alignment surfaces on the front cover.
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.