It looks like the clutch and both chains are in pretty rough condition as well. You might be able to clean the chains enough that they will work, but i'd recommend new ones (they should be 420).
What's wrong with the engine. If it just runs horribly then clean the carburetor. If that doesn't work then make sure that it has good gas, make sure that it has spark and the plug is clean, and check the valve lash.
I'd say that a torque converter wouldn't be a bad upgrade. And you have a predator with a drilled and tapped crank, so it should bolt right up. You might need an engine riser kit, but that's just two pieces of 1" square tubing and longer bolts.