They are completely different engines. A couple of major obvious things: chevy's have a stamped steel timing cover and a water pump that is separated from the block while pontiacs have a cast aluminum cover with the water pump integral (like a Ford), pontiacs have a valley pan with the intake floating over the top while the Chevy intake covers the valley, the pontiac distributor turns the opposite way, the pontiac engine is a lot wider, hence the engine offset to the passenger side in the bird.
