How do you change the oil pan on a 350 Chevy?

You will need to raise the engine enough to clear the frame "cross-member". That means you need to disconnect the motor mounts and probably use an engine lift.

Once you have about 6 inches of extra clearance you just remove the bolts that are around the perimeter of the pan, clean all of the surfaces, use a slow setting automotive gasket sealer to seat the new gaskets then put it all back together. The slow setting gasket sealer gives you time to reassemble without being rushed.